1968 Barracuda
Was on the dash in 68 as well. This issue has been discussed on many forums, many times. And I hate it for this guy just trying to sell his car, but most people interpret the law as saying IF you move a VIN tag from one body to another, you've committed a federal offense.
That's what I meant by foot, meet bullet. You've shot yourself in the foot by swapping numbers on bodies. I really am sorry for you, especially if you're between a rock and a hard place and HAVE to sell the car, but you're pretty much screwed.
Hopefully this will all work out, and you get what you need for the car.