My first Z was a 77 280z, freakin mint with nice paint and wheels. Anyways it was a mild stroker with factory fuel injection running it. I put 10k miles on it in a year, only problem I had was the temp. sensor went out. As far as the fumes, well buy new tail light seals, hatch seal, extend the tip out some, I had no problems with mine. I also spent some money and put a new AC compressor on mine and recharged it. That AC would freeze you out of the car and the heat would make you sweat, damn why did I sale that car!
For the past 2 years I drove an 87 z31t and put 15k miles on it, good car and didn't give to much trouble. Had to put main bearings in it but that was a one in a million bad luck that happened to me and no one else I have ever heard of.