Ford 460 if you didn't know that already. It may have been indoors, but likely in unheated space for a long time. Just my opinion, but I'd pull the engine apart and inspect, only costs a gasket set to know. Engines in storage long term cross the dew point many times and condensation occurs. Now if you told me they went and started it every 30-60 days, that would be different. Add in the flaking clear(not original), not a desired Glastron trailer, and several other unknowns, I'd be hard pressed to offer his asking price of $8900.00 I love the lines of the 20 jet, probably the sexiest boat tail made.