Having paid top money for my GTV6 and still found items far from perfect, I'd agree with the previous advice. Have someone who knows GTV's look at your prospective purchase.
My GTV6 sunroof drain pipes exit just behind the front wheels inside of the wing. Two fist sized holes each side, partially covered by plastic sill covers, £600 plus to have new metal let in and resprayed. Fab job tho.
The car has already had:-
Scuttle work (open the bonnet put your head in and look back towards the passenger compartment under the screen)
Wing tops (handy little ledge inside the top of the wing for mud and damp to collect and start the rusting process)
It still needs to be perfect:-
screen out as it's starting to bubble along top edge
Joint between front wings and front panel is bubbling
All four window guides are heavily corroded (and that's inside the car, god knows how?)
If you are looking for a cheapy, get a mint body and poor mechanicals. As a lot of parts interchange with the 75, (series 3 GTV's) parts aren't that difficult to come by.
Trim, interior bits etc aren't so available.
You'll love it once you have it as I do mine!