Interesting conversation. My theory about old car parts in general (though I could be wrong) is that there isn't a big enough market for many of these new old parts to get an economies-of-scale based retail price advantage, but there is still enough demand to make it profitable, so they make the parts cheaply overseas so that old car guys get the impression that the price of a fuel pump for their old Y-block isn't that much more expensive than the fuel pump for their old '99 S-10 Chevy pickup. I generally find that old collector car parts such as these aren't quite as good quality as parts for newer and more common daily drivers ('90's and later) though I've certainly run into problems with parts for later cars, too.
Since many or most of the old collector vehicles aren't used as daily drivers, it could help mask the problem. They might see 10,000 miles or less every five years instead of every year.