Depends. If you want to go fuel injection, I'd recommend a 280z, and swap over some 240 bumpers. You'll already have rear discs, a r200 (beefier) rear end, and it is setup for fuel injection from the factory.
If you go the route I'm going, with a 240, you'd have to redesign your fuel system a bit to make it be able to handle the injection system.
There is no such thing as a rust free Z. And if you were serious about it, be willing to ship from elsewhere in the country. You will still save yourself thousands of dollars, and hundreds of hours of repairs. Even if it cost a grand to get it to you.
Search the classifieds on Hybridz.org. I feel you'd have the best luck getting something decent there.
10 grand is about what I believe you'd have to spend to get a (preferably running) 240.
The 240 is definitely the most sought after, so they command the highest prices.
You can pick up 280zs for dirt cheap comparatively.
Another thing to note. There are basically NO BOLT ONs for these cars, so you will most likely have to design and fabricate a lot of stuff yourself if you are serious. (Something I regrettably found out later)
I'm definitely going fender mirrors too. Passenger door has the mirror shaved, and I have a real nice driver's door I'ma paint to eliminate the stupid bullet mirror. I'ma make mine outta carbon
