Can you build a whole car from aftermarket repop parts?

Read in a car magazine a couple years ago that you could build a '57 Chevy hardtop from aftermarket parts. No matter which Mopar you want, it's nowhere near possible, and only a very few 60s and 70s models have parts available There are almost no aftermarket parts for older Chrysler products. I'm doing a '56 Plymouth, and except for a few exterior patch panels left over in the system, l have had to make most of my sheet metal from scratch.