By the time I’m done ‘restoring’ it, what would be left of the bird we see in the photos, anything? Or would it be the provenence and patterns that would remain?

Not sure that if you wanted a flying Beau you would choose a salt water wreck in the first place. To my knowledge no (long term) salt water recovery has ever been restored to fly. The only exception I can think of being the Corsair that ditched off the beach on the eastern coast of Florida in the early 90’s, but it was only immersed for a day or two.