You will have a hard time finding a restored Z that is not ‘done’. Seems silly to buy a restored Z, only to hack it apart again. You also will not find a Z that is not restored and has no rust.
If you don’t want to deal with rot, you wo’nt be building any S30(240, 260, 280) Z, imo. At best you’ll be getting a car that is 26 years old. (1983 280ZX)