I had a 240Z in Australia - the importer brought them in with a three speed automatic or a five forward speed manual. The fifth gear was an overdrive and it was awesome ......... The greatest deficiency was braking -- very small disc front brakes and read drum brakes. An after market option was disc brakes front and rear that helped. The 240Z also floated at high speed so an airdam was offered that would pull the nose down to the ground. The floating was a serious deficiency. The 240Z was really a cheap copy of the E Type Jaguar. The 240Z used brakes and transmissions off other Datsun sedans, so it wasn't especially designed, but that straight six cylinder engine was awesome. It should be a collectible, but they are rust prone so be watchful when looking to buy.
My least favorite Z is the 350 and 370. Nice cars but not great cars to me. I love the old 240/260 Z cars myself but I am partial to the 1990-1996 Nissan 300ZX Turbo myself. It's just my favorite Z. Maybe the 400Z or whatever they call it will bring some of that magic back. I think they should call it the 300Z/ZX Turbo myself.