Nice ride! Always liked the Z cars. I had a 79 280zx and an 82 280zx turbo. Fun cars. Ever consider tracking down a diesel and going bio? The Datsun/Nissan Diesels in the Maximas (like the '82 pictured) should drop in pretty easily. Shouldn't be to difficult of a swap (as far as gas to diesel swaps go).
But if you are just looking for a $500 commuter that gets good mileage...I would have to agree with SVO. Keep your toy and get a metro.