dont you dare put a v8 in there. and also remember that if it hasnt beeen driven very hard, the motor should be fine. and its an auto so it cant have been driven THAT hard. in a rotary there are a lot less moving parts, giving it a much longer life.
Um, you should not be giving advise on this subject as you clearly have little understanding. Sure the Wankel engines have less moving parts but in general, they are MUCH less reliable and durable than piston engines.
Everything duo2999 said is pretty much correct although even I would say 200k miles, even on an N/A, may be pushing it. The N/A's generally have a much longer life than the turbo motors (my '89 has 105k and is still going strong) but they can still pop easily. Definitely have the guy start it for you and make sure it's started cold - you'll want to find any cold start issues, if any. Generally a good thing to ask is the oil consumption. If they say it doesn't consume any then they're either lying through their teeth or they don't have any idea how a rotary works. In either case that's a red flag. Other than that, like duo said just check for weird sounds, smells, sights, CELs, etc.
Price-wise $1500 seems too high based on your description. If you can point out key flaws and realistic figures to correct them offer like $500 and go from there as mentioned above. Even if everything looks "cleanable" remember these cars are 20+ years old.
As far as swaps go, personally I see no reason to own an RX-7 if you aren't going to keep it Wankel-powered. There are plenty of V8 swaps out there but if you were dead-set on going that direction I'd show some effort and at least go with a fuel-injected LS1 or better. The over all weight of the engine is very similar to the stock 13B so the "balance" of the car won't be affected too much at all. But again, it's my opinion that if you want something with that particular body style with a piston engine you're better off looking for an S13 240 or something like that. If you plan on keeping the 13B and swapping transmissions that might be tricky, but certainly easier than the task with a Protege or something similar. There were lots of these cars made so used parts are pretty easy to find at junkyards and whatnot. Just remember as far as drivetrains go you cannot mix and match TII and N/A parts. Without custom parts a TII transmission requires a TII driveshaft and a TII differential, etc. and the same for the N/A. It's the wiring harness where things get tricky.
If you have any other questions feel free to ask. I've only had my '89 GXL for about two years now but I've learned a lot and I'm currently in the process of a full rear-end overhaul. There's only a few of us RX-7 owners on these forums so don't be too disheartened if you don't get a response for a couple days.
