Tony, I totally agree with Fleetwin regarding checking under your power head for clogged water bleed holes. He figured this out for my 10HP, and by cleaning out the passage it fixed my hot exhaust housing. It was full of carbon / sludge from the poor oils used in the 50’s. The hole was so clogged I had to dig around with a pick before I could even find it. Note however it was a 10HP not a 7.5, so yours may be different, but definitely worth a poke around.
In addition another overlooked part to check for strong water cooling is #90 (302497) in the attached picture. The upper water tube grommet. It’s a bit hard to find and check since it’s located way up in the exhaust housing.
Post some pics when you get your head off. Good luck.
Bob D

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