Parts and service would cost an arm and a leg i'm sure. That's why I'd make sure it was running fairly well now. Not about to start and restore anything from the ground up.
I don't know about Corvettes though, the new ones are really nice, my neighbors have 2 of them I think. I like the old ones from the '60s as well. Corvettes can be expensive on parts and service as well. One of my dad's friends was restoring one. He decided it was going to be way to much for him to restore it to the orginal condition. This coming from a guy I consider to be doing fairly well money wise. His wife drives a '95 Corvette or something similar to that year.
How much have you had to put into the RX-7 to keep it running well??