Here is one of the issues I have regarding "original vehicle" when talking about VIN tags.
The picture below shows a first gen Camaro being "restored." The only thing that will be original on this thing is the inner structure. And, even some of that has been replaced with after-market pieces.
So, when does the "original vehicle" become not original? The parts replaced on this structure will be close to - if not over - 95%. If they are going to this level they are not installing the original interior, sub-frame etc. How can this be original? How can you reattach the VIN tag to this and say "it's all legal."
How is this any different than attaching a VIN tag to a Dynacorn body using the original front sub-frame, fenders, hood,motor, rear axle, seats, interior, etc etc etc? The only thing replaced was the body.