Re 70mm, I have seen two 70mm Star Wars prints, only one was in projectable shape and both were far too faded to red to be useful for restoration of the image, it is extremely likely that they all are far too faded now.
Plus 70mm is cropped at the sides, so I don’t think it will be a lot of use for the visual restoration.
Even if it’s too red faded, could it not be used for luminance detail?