Hello: My main concern would be with the gas control and safety. If the basement was damp, that’s not so good. I would makes sure there are no bugs in the control and probably would rinse out the tank outdoors, with the drain valve removed, so anything that might have crawled into it years ago doesn’t get into the plumbing. 😛
If the tank works otherwise, make sure it has a magnesium anode and just to be safe give it a new relief valve.