Anakin's ghost??
The ghost effect shouldn't be TOO hard to change, given what we have seen from that one screenshot I posted earlier. If Lucas has the original film that was shot (the ghosts were obviously added later), re-combining the individual elements (just as they did in 1983) shouldn't be tough at all.
What about Anakin himself, on the Death Star? If that gets changed, THEN I can see some trouble of 'Gumpian' porportions.