Congrats on your buy. These cars are great.I'll only speak about what I know stay away from the TH350 and TH400 your overall gear ratio is way too low. I have a TH350 and it sounds way too tight at 70 MPH. 2nd thing buy this book it is expensive but you will use it all the time you have your Z http://www.jagsthatrun.com/Pages/Datsun_Z_V-8.html