I just finished rebuilding a 1976 15 HP Evinrude head to toe over the winter that had probably seen its entire life in salt water. It was rebuilt before in late 90's, and whoever did it (34Hat?) used gorilla snot, aka Mercruiser Perfect Seal, aka permatex "aviation form a gasket" on all the threads which allowed all the bolts to come straight out without twisting off a single head. I used it to reassemble the entire engine.
In researching what this stuff was, I found out its the preferred anti-seize for bolts on marine engines, and I'll vouch it works. Problem with real anti-seize is it's actually a hodge-podge of different metals mixed into a paste that can make for allot corrosion in a marine environment.