I think some scenes from EP2 are needed to show how Anakin turns…
Perhaps start with Anakin’s Tatooine story from EP2 and use the dreams to show premonitions for the events of EP3.
Perhaps use part of EP2 count Duku to tie in with Palpatine’s kidnap.
EP3 deleted scenes help with the story, but they make the film drag on a bit. So pacing needs to be changed also. Again, I’d try to fit some action from EP2, probably the Obiwan X Jango Fet fight.