Or you could take a look at a GB that has sound teak decks and rust free tanks.
The key to maintaining the decks, and protecting the top of the tanks, is to pay attention to the seams and bungs (plugs). The bungs are easy to deal with the seams a little more challenging. I've let the pros maintain my deck seams and I stay on top of the bungs. The other, maybe more important, source of water intrusion are the deck fills; these need to be inspected and re-bedded if necessary. I had a quality boatyard re-bed ours when we bought her, not very expensive and provided peace of mind.
Our '91 is on the market, come take a look.
YW link: 1991 Grand Banks Heritage Classic Power Boat For Sale - Boats for Sale, New and Used Boats and Yachts - YachtWorld.com