New repro body parts connection?

AMD is the best fitting stuff available. No reproduction part will fit perfectly, the FACTORY parts never fit perfectly and the fit varied from one car to the next, the body tolerances on these cars are all over the place. And that was 50+ years ago.

With large reproduction parts a big part of the price is the freight shipping, and how that gets advertised will change the price on the part more than anything else. As in, if you see a floor pan super cheap somewhere, you can expect that doesn't include the freight shipping. For example, Summit's advertised prices are not the lowest. However, their freight free is also not 100% of the freight cost, as in shipping a fender might cost you $20 extra at Summit but $100+ somewhere else. So, when you're pricing parts make sure you're comparing the price that it'll take to get it shipped to your door, because most of the "cheap" advertised prices have a ridiculous freight charge that gets added.