Mike,
I love the looks of the 510 but would never want to own one. Like you said, the SR20 and RB seem to be the hot ticket as far as swaps, but you're also talking about a lot of fabrication and work. If you're going to go through the trouble of a swap, forget about a KA and get something worthwhile. F20c has been a pretty neat swap for a car of that size, but I think personally I would swap a stroked L28DE from the 280z and be done with it.
There's a lot of people who follow the 510s, but there's a very limited amount of original parts around, anymore. Finding one without rust, un-molested and in good condition isn't easy by any means so expect to pay a pretty good amount for even a shell.
Driving one daily is pretty much out of the question. Good luck finding one that runs reliably, as the L16 that came in those were obviously carbed, and probably need overhauled before anything. You'd be looking at converting to EFI which will be a pain in the ass, or converting to weber side-drafts which can be a PITA as well.
Oh, and you're definitely not finding anything in the midwest for it.. you'll be doing a lot of parts searching in the west, which a lot of those guys won't ship anything for whatever reason.
I know someone was waiting for it, but why do you think I like the quad headlight setup on the '80s Corollas? It resembles the 510 quite a bit, and the best part is, parts are easier to find compared to the 510.
http://img25.imageshack.us/img25/7951/img7821copyui0.jpg