Gotta think resto of any warbird this far down the road must involve an awful lot of new parts - the skin, most of the ribs, all the electrical, all the gauges... Damn little of the original left. I've heard it said that as long as you have the ID plate (basically the VIN for the aircraft) you can build the rest and still call it the real deal. How much of a B17 submerged for 70 years or so will remain airworthy?
No idea how much is usable to put a drowned B-17 back in the air but it is great someone does it.
My wife (girlfriend at the time) and I where driving to Toronto so for a break we stopped in at the RCAF museum at Trenton. Parking around the side of the building the shop doors where wide open and we walked over to have a look at the Halifax that was in the process of being restored) fully expecting to just see it from the doorway. We where just standing there taking in the view when we where warmly invited in and given a walk through of the work shop and people doing it. The average age of the volunteers was...........lets say senior, when they broke for lunch our guide pointed out there was well over one thousand years of experience seated at the lunch table. He also showed us one of the rebuilt engines on a stand that pics of it at time of recovery looked like a ball of mud and rust, the motor on the stand looked like it had just arrived from the factory AND, and this was the coolest thing, he put the power to it and turned it over!!
http://airforcemuseum.ca/en/special-exhibits/the-story-of-halifax-na337-2p-x-part-1-of-5