I'm considering purchasing an owner finished Westsail 42. The original owner bought the boat as a hull and deck with black iron tanks and Perkins engine installed in 1975. It basically sat in a warehouse until 1999 when the second owner bought and finished the boat. The boat saw light use since 2001 (900 hrs on the engine). These tanks are not showing any signs of leaking, and are sitting up out of the bllge resting on floor timbers. The bad news is that there really is no access to these tanks with no inspection ports or access through cut-outs in the sole, or access through the engine room. If they leak, it'd be a major project to replace them.  Any thoughts on the longevity of these tanks? Any options for cleaning these tanks without an inspection port? Any comments would be appreciated.

-Jim