Boyd Coddington of American Hot Rods was charged for this very thing, the Ship of Theseus, also known as Theseus's paradox, is a paradox that raises the question of whether an object which has had all its component parts replaced remains fundamentally the same object.

However, he replaced old with a new design and replaced engines with another design and so on. You would be replacing a coupe shell with a coupe shell so really it's not an issue.

I had a re-shelled pug 205 that was hit by a motorbike and damaged the original beyond repair, the car had to go for an inspection, a bit like an MOT but nothing was registered against it and it was just a case of swapping the VIN over and re-etching the chassis number on the chassis.