uh, oh.... that's a touchy subject! Many will have strong opinions on it.
Most will say you're doing something illegal (swapping VIN's), creating a fake musclecar, and out to commit fraud by putting a pedigree on a turd to get some big bucks at resale.
Others will say you're just replacing another part (body shell) with a better one and it's no worse than putting on replacement floors, fenders, and quarter panels.
Best bet is to contact your state DMV and see what the laws are concerning moving a VIN to another body. Some states allow it, some don't.
Trouble is, even if you disclose to a future buyer the car has been rebodied (and price it accordingly), a future owner could claim it's an original car and sell it for 'original car' big bucks..... which could be considered as misrepresenting the car, or fraud.... and someone could get burned down the line.
Ask your DMV....