If it's a TT then you'll need to have the motor checked out along with the turbos. I won't lie the Z32 cost a lot to maintain because the VG30dett is cramped in the engine bay.
Also have patients when looking for a TT they a very hard to find in good shape.
Here is a link to help you answer your questions.
Nissan 300ZX Enthusiast's Buying Guide - Sport Compact Car