Hold up.
The reason the Jessie mod is 7h only is because 7h is able to hotswap files in during the game's runtime depending on certain variables (what field ID the player is on, some in-game variables like Game Progression, what Key Items you have, etc).
So what Jessie mod does is, it swaps Tifa's Battle Model and Menu Portrait with a Jessie version while you're in Reactor No.1. Once you leave, the game swaps back in the original Tifa Battle Model + Menu Portrait.
If you put the Jessie mod files into, say, R06, then Tifa's battle model + menu portrait will always be replaced by the Jessie versions for the entire game. I guess this might not necessarily be a bad thing if you were wanting it to last a little longer than the first Reactor. You could also take those files back out once you're clear of Reactor 1, I guess.