This might be a little ambitious, but I think it would be interesting to use some visual effects to alter Palpatine’s appearance.

Pre-transformation Palpatine looks more like Ian McDiarmid with white contacts, to me, instead of looking like the Emperor. I don’t know if that makes sense, but there seems to be very little make-up on him that we associate with the Emperor, beyond making him extremely pale.

I think it would be interesting if we could make Palpatine look more undead and zombie-like. I picture him without a nose, rotting flesh around his mouth exposing his teeth. This could be done in after effects by motion tracking his face and then applying various “undead” elements to it. I imagine the sporadic lighting could make it a bit of a challenge, but on that same token, him being obscured by shadows and darkness could help sell the effect as well.

I just like the idea of playing up Palpatine as this lich, basically, whose spirit desperately clings to what is left of his undead body. I think you could either go in two directions: he is a clone, or he is possessing his undead body. I’ve gone back and forth on this, but based off the visual clues in the film, like the dead eyes and rotting hands, I think it would be better to play up the undead, Frankenstein, angle. It would also better differentiate his resurrection in IX than how it was depicted in Legends.