I put that toghether just to see how it would look like. The video on YouTube has almost every shot of Tarkin in the movie. You could try contacting Shamook to see if they have the rest of the footage/source quality files, they have their email on the about page of their YT channel & says they’re open for collaboration, might have better luck than with derpfakes. And judging by the description on their video they might appreciate to have a version of Rogue One without the dated CG Tarkin.

Otherwise I would be willing to painstakingly mask the footage from the Youtube video.