It's funny you mention the 300ZX, I ran a TT manual for a short while a few years back after having run a Supra turbo auto.The ZX was much quicker and felt more planted.The engine was a little tired but I am not particularly hard on my cars.My mate who bought the car off me is, he gave it absolute death for twelve months then sold it to Z world for very near what he gave me for it!
Regarding the Supra, very well made,good build quality, head gaskets are an issue and beware bottom end rumble.Listen carefully on cold start - bottom end wear will result in rattle until the oil pressure builds.It will sound fine once the oil gets round, but have seen them throw a rod in extreme cases.