Biggest problem areas on the 240Z in no particular order include; The battery tray, rear hatch, rear tail light panel, and the floor reinforcements from the frame rails to the floor pans are all extremely rust prone and I would STRONGLY advise poking it all with a stick and looking hard and well at them. The only other thing worth checking out is the main fuse block under the hood as they are notorious for having issues with age.
Driveline stuff is about the same as any car so I wont go into much detail there.