Just an FYI, I was reading on another forum that now some of the collector car insurance companies are checking VINs and rivets now, as a means to deny a claim. Some are even checking engine #s against body numbers, and without CLEAR documentation as to where the donor came from, they can actually legally deny. They enter into contracts with the legal assumption that a collector or classic or special interest car is numbers matching, as it should be according to law. Be careful with numbers, and be sure to clearly document everything.

To the OP, I would take several pics of the damaged frame with vin attached before transferring to the new frame, and use the correct rivets just to be safe.