I would use adigitalman's solution for the emperor - new emperor, old dialogue - achieved by careful editing of the audio.

Really don't see why people are so attached to the old emperor. Looks like what it is. A girl in half a chimp mask. And Clive Revill's line delivery is uninspiring - to say the least.

It was an absolutely awful element of the original and quite right it was changed to match ROTJ and everything else. Just a shame Lucasfilm messed up the dialogue.

Great idea for an edit, Funcha!