Some things (like this Porsche frame) shouldn't be considered restorations. How can you call something a restoration when it looks like they will have to source 99% of the car from somewhere else. It becomes a Frankenstein car at that point.
A vin number and a rusty frame (that they will add artificially to) does not make the car authentic to me. You could flip it around, and add the original headlights from this car to a complete replica, and claim the same thing.
I guess you can do/claim anything you want if you have enough money to burn.
Actually, Vince is right. The Vin number and photos of how the car was found are very important. It's all part of documenting this is a legit and rare (1 of 1700) 1955 Porsche 356. You are also right, when it's done, probably 40 percent of the body will be completely new.
When people say older cars were better than newer cars and they point to a Chevelle that has a new frame, new suspension, new breaks, new engine, new transmission, and the body has been repainted using modern techniques, it just baffles me. To me that's a brand new car.