You said "shampoo commercial" and the roulette wheel that is my brain immediately stopped on Jang Hyuk. I got nothin’ else.

Won Bin - making his glorious comeback to dramaland after a 20 year hiatus as our hair patting psychometrist (we want those Sky Castle ratings okay!!)

Shin Hye-sun -as our time travelling heroine she has experience with time travel, bringing down powerful people and falling in love with rich guys, plus shes a hoot.

Kim Mi-kyung - as modern era mom
Kim Mi-kyung - as Joseon era mom

Cheon Ho-Jin - as the evil minister, no Joseon era story is complete without an elderly evil Minister.

Ji Chang-wook - as the loyal sword fighting sidekick of our male lead who will die in episode 15

This is pure genius plot.

I say Jung Il Woo and Kwon Yuri for the main characters, their chemistry seems timeless at this point.
Or Jung Ryeo Won as the historian, aided by practically any male hero.

among sidekicks: Min Jin Woong! his energy and characters are always great and pleasant to watch.

The shampoo is tricky, but I would go with whichever brand is famous for flower scents and extracts.

Because I had these two in mind even before reading the prompt: Lee Joon Gi & Jeon Yeo Been.
I was recently watching some BTS/making of Vincenzo videos and it made me wonder what it would be like if she and Joon Gi were paired together.

And then I see this prompt involving the Joseon period and eccentricity and it's like well, that works haha.

The image of this gives me Beautiful Gong Sim vibes, since the ML had a very profound relationship with the FL's wig/hair. 😂 But the "crazy" woman part just makes me think of a FL like Bong Hwan-ah (Mr. Queen) saying "No touchi" 🤣

So I feel like the ML would be desperate to touch her head, but she wouldn't let him. He touched her hair by accident a couple times and now he's obsessed with the gibberish on her head (while she thinks he's a weirdo).

And that's why he decides to marry her.
She just agrees to it because he's a nobleman and she knows she could do way worse in Joseon.
Also, he's part of the clan so maybe she can exchange info for a few pats on the head?

Kim Seul Gi X Rowoon
or
Jin Ki Joo x Song Joon Ki

...I wouldn't mind a reunion for the leads of He's Psychometric, tho. ^^ *coughs in ahgase* they would be perfect for this.

As I was reading the plot, I was thinking of a reunion of "Live up to your name" main stars, Kim Nam Gil and Kim Ah Joong.
That insane chemistry needs to be shown again.

My pick: Ahn Bohyun and Kwon Nara.

I'm definitely going off script at some point but...

Our psychometric modern day guy is Kim Nam-gil.
Our Joseon lady is Shin Hye-sun, the prime daughter of the Andong Kim clan. Note that this daughter is not a member of the royal family.
Kim Nam-gil approaches her because he thinks that's the best way to deal with the situation: attach yourself to the most powerful lady in the family after the Queen Dowager. What he doesn't know is she's fed up with her family's antics and power trips and has been looking for a way to curtail it whilst maintaining the grip and status they have on and in society and the royal family.
This begins an enemy to lovers story on the part of Kim Nam-gil and a blossoming love story on the part of Shin Hye-sun.
What's a love story without a second lead. Cue to: Prince Yi Hyeong-jung played by Wie Ha-joon.
The house of Yi are definitely tired of maternal families controlling royal affairs but then they can't have marital alliances with non-powerful families cause the royal power is weakened, thanks to the two families that caused this - Andong Kim and Jo. Both families throw the country into disarray during crown princess or Queen selections.
His father - Ahn Nae-sang is currently married to Park Ji-young of the Andong Kim clan. Hyeong-jung's grandmother is Kim Hae-sook of the Jo clan.

Shin Hye-sun's well-known reputation makes her a good candidate as a bride for Wie Ha-joon, which is a bonus for his grandmother but a no-no for his mother. His mom is instead pushing for Shin's cousin(I'm yet to find an actress to cast in here).

KNG and SHS begin this romance that becomes the talk of society. A talk that soon gets into the ears of WHJ, who had been hoping she'd make it into the CP selection and has been trying to woo her after he noticed KNG. To thwart their possible marriage, the royal family announces the marriage mart. However, thanks to QD KHS's court lady who's a friend of SHS's mom, the info is leaked prior to the announcement to Shin's family so they plan their marriage the day to the announcement.

Shin Hye-sun's blossoming love story turns into enemy zone when she learns about his intent prior to his approaching her. More pissed was the fact that he knew about her stance with regards to her family and still approached her with the same mindset he had initially. She cancels the wedding with KNG, enters the CP selection and wins, to the chagrin of both Queen and Queen Dowager: who wants a daughter-in-law that'll never ally with either of them.

KNG later falls in love with the uncasted cousin of Shin(who never wanted to be a part of the royal family in the first place
[weird right] and always had eyes for KNG)and that provides the stepping stone for the maternal families Jo and Andong Kim to lose the powers they've cultivated for centuries. Both women partner together and provided the check and balance the royal family needed to gather power for themselves.
Both loves...

If the premise is the nobleman has psychometric skills as the “ability to measure and interpret the essence or history of a person or thing through touch,” he is able to see the strongest memories tied to them.

Historian (Jung Ryeo-won) researches her family register to find she had a distant relative who was a shaman in Joseon (Lee Chung Ah) who was executed for trying to de-stabilize the ruling Kim clan. A nerdy university co-worker Physics Researcher (Kim Kwon) believes he has created a time machine. She charms him into showing her how it works. She sets the date for Joseon period, but as he attempts to stop her they fall into the machine to be transported back into time. He is upset because there was no return time line set in the machine . . . they may be stuck to die in the past. When Kim finds out her plan, he is appalled by her recklessness to remind her of the butterfly effect in changing history. She does not care. They split up.

Jung spends a year trying to find her Shaman. When she does, madness has begun set into the Shaman as the Kim clan has started to crack down on non-science religions like shamanism. However, they quickly learn that if they are both in the same room, they can read other people’s minds. They do this for weeks to avoid capture as there is a bounty on the head of the Shaman.

When the Royal Guard comes to arrest the Shaman, it led by the King’s stargazer and trusted advisor. The guard commander is to take Shaman for trial but Jung is shocked to see the Physics Researcher is the Stargazer! When he enters the room, a psychic connection is made between Kim, Jung and Lee that allows him to “hack” other people’s minds. “A brain is nothing more than a computer that can be re-programmed to do my bidding.” With this new power, nobleman changes the commander’s mind and memory to make him believe he is mistaken and that he has insulted the family of his bride-to-be. Jung is shocked that Kim is seizing power by using his advanced knowledge to destroy history itself. But in order to live and maybe return to their time period, Kim blackmails Jung into marriage contract with the Shaman as her sister so they can be together to read and re-program minds of the Royal Palace officials, including the King.

Just as Kim is about to overthrow the King, his body begins to tingle and a blue aura starts to seep out of his body. In a panic, he runs to find Jung and Lee. He finds Jung in a similar state. The Shaman barks at him that his evil has finally met its match as she dances around the room waving a rattle made of human bones. When Kim touches Jung’s shoulders they are in a flash transported back to their time. When they awake, they find themselves in dystopian Seoul where current Korean society has common people leading wretched, dehumanized, fearful lives. They go to the university but it does not or may have never existed. They begin to blame each other for changing history when a band of filthy peasants come across...

Since it is taking place in Joseon, it would be weird for a shampoo brand to be there unless it traveled with her. So she could be transported in time while she had been shopping for her shampoo. When the shampoo is freshly used, it would temporarily block the psychometric's powers making it impossible hair--which neither realizes until the 12th episode when the realization that her hair gives away her thoughts would make her say "tress so me!" At this point, she would wig out to protect herself.
In episodes 3-11, he would brush up against her wondering if he should lock her up so he could comb for clues while the strands of time slip through his fingers. He goes to and fro on this issue because he can't help but treat her with tendrilness.

This is the punny tale I imagine for this hair-raising scenario. Feel free to nitpick.