Anything can fit with a bit of bending, cutting, welding and drilling. I think bmw seats would look way out of place in a z32. I think finding decent second hand ones would be a the best option. If you insist on different seats. Try looking for cheap recaros, honda civic type r, vauxhall corsa vxr, renault megane 225 recaros come to mind. Being recaros you could buy the rails for 300zx and fit them straight... i think. But dont take my word for it. Orherwise i kind of like Chrysler Crossfire seats and i think they wouldnt look too much out of place, but they would definately need custom fabrication to fit.