I must say, I am really impressed by what I am seeing, especially considering the fact that I was honestly expecting this to never come to actual fruition. Unfortunately, I cannot provide any real help though as much as I wish to, though I will give some minor tips if I think of anything useful, although you pretty much have your priorities straight for the most part and I can appreciate the no DNR aspect as well as the implementation of the original theatrical mix (though I hope it’ll be noise reduced, but if not, I’m sure someone can do that easily enough; not that I’m expert on any of that really though, so sorry). The only thing I can really say is that I recommend trying to refrain from screwing with the colors as much as possible to retain the theatrically intended color scheme (rather than trying to create a “clean, natural” look). I would recommend trying to simply reduce the fading and leave it at that.
As I said before, I wish I can say that I can be of help, especially as a fan who’s seen nearly every Godzilla movie out there–with this being one of the few exceptions–but sadly, I have no skills in any of these departments really nor any spare cash currently.