I have looked up more Tarkin deepfakes and found a few that contain most of the missing shots. The quality varies, and they’re only 1080p, but I think they would still mix better with Shamook’s footage than the original CGI.

derpfakes has done the first Tarkin scene in full, which adds two missing shots from this scene:
https://www.youtube.com/watch?v=6Zn1vt9vdwU

birbfakes did the scene on Jedah, which also adds a few more missing shots. It would blend pretty ok with the rest:
https://www.youtube.com/watch?v=BcEtPLsJ-F0

Jarkan did a bunch of scenes. Though the effect is less convincing, there is one shot that’s not on the other videos:
https://www.youtube.com/watch?v=gg1LPc6WUdM

If I’m not mistaken I believe that only leaves one shot I could not find, which is when Tarkin first arrives on Scarif and says “Lord Vader will handle the fleet…”, which actually doesn’t look that bad since it’s a medium shot. So I believe it is doable.

If anybody finds other high quality sources, they can send them my way.