I agree with Frank, we had a guy at my fathers Marina who had a 470 in a Chris Craft Scorpion. The engine had a lot of time on it and he wanted an excuse to get a new engine. He ran the crap out of it and it wouldn't blow up. He then ran it on the trailer without water at 3000 RPM's. It ran for approximately 30 min and it got so hot that it started to miss, RPM started falling, and then it finally quit. We thought for sure that it was done for. The next day he went to the boat and hit the key and the SOB started right up and ran fine.
I think that he ended up putting some lead pellets down the carb so it would get to the combustion chamber and raise cane. The only thing that I can think of besides the charging problem is the engine would shake excessively at idle, I was told this was due to its large displacement and it only being a 4 cylinder.