I think it took me like a week of tinkering with it during evenings. just because I took the opportunity to disassemble the subframe assembly, replace all of the bushings in the rear end, and clean the rust off of everything. If your only goal was to get a new tank in, it could definitely be done in a weekend.
getting the new tank in the car and the straps installed was kind of a pain to do by myself while laying on my back. other than that, the job isn't too bad at all