Hey Doug,
I'm thinking the overheating is from another source. I run a 235 in my '40 and never had much of a problem with overheating even with the short-shaft pump. I would suspect something in the radiator system - plugged radiator, bad pump, collapsed hoses. Or, a problem with timing. If it has recently been rebuilt perhaps the crank and cam are not phased correctly. Just a thought. Hope you find it.
