The hard part really is just finding appropriate footage of Hayden to use. I’ve scanned through ROTS a few times (and the various deleted scenes) and never found anything at the right angle or which wouldn’t be a super obvious lift.
There’s the scene of him saying goodbye to Obi-Wan, or the balcony scene with Padme.
I mean this is a pretty great smile
Eh, it looks better later in the shot and a few shots later, with teeth showing. This nails it more:
Still, the lighting would make it very obvious that it’s not from the original. Some method of fixing it would be needed, but that’s simple.
Still, I’d say manipulation of more straight-on shots, interview footage from now, and/or deepfakery would do the trick.