It would be nice to have Finn’s goal after his escape in TFA be to inform the resistance of the existance of Star-killer base. After all, he mopped it’s floors and…somehow… Knew its weak spot.
The hardest scene to re-edit would be at Max’s castle on Takodana. His motivation in that scene is to escape the war.
The Last Jedi wouldn’t need much adjustment, as he believes the war lost at the beginning of the film.