[TimG]

I think that before the science of trim tags evolved, many folks changed trim tags on all kinds of cars. The originals were lost or tossed and a reproduction put on to reflect what the restorer wanted. Now trim tags are, with out a doubt, harder to fake than an engine block.
I owned a '69 Pace Car that burnt in a fire, the trim tag melted. If anyone rebuilds that car, they'd have to replace the trim tag with a reproduction due to the loss of the original. They could include all of the original data, but it would be a reproduction on an original Pace Car with the original engine (what's left of it). It would probably raise lots of questions.