Its one of those stupid semantics illegalities. It is in fact a federal felony. But...
If you have a car, and you replace every single part except the dashboard, that's legal. If you swap the dashboard from one car to another taking the VIN with it, its a felony. You could say that you had a 79 that wrecked so you took parts off the late model to repair it or something... but if any scrutiny comes your way, make sure you have something to back up your story... pictures, receipts, anything. But... you will most certainly have to use the 79 dashboard or a reproduction of one. Its one thing to give the appearance of hanging some sheet metal on a body, but a full interior and dashboard swap is unlikely which will be a huge red flag. Once its suspected, all it takes is a keen eye to see if the VIN tag has been swapped.
I have seen it done before, mostly because they knew it wasn't immoral. A buddy had a motorcycle without a title, so he bought a frame for $20 off CL that had a VIN and title. Instead of spending weeks transferring all the parts to the new frame, he just swapped the VIN plates to the old bike. So, he's not going to hell, but might go to jail.
...but I doubt they'll send a forensics team to find out if the VINs were swapped.