These pictures are from a 75. In case you don’t get this deep into yours, levers in the block run on eccentrics on the crank that operate the valves. My son-in-law uses this motor for fishing and running around the lake. In 6 years there have been 2 issues. After 4 years the original cork gasket for the cover on the head, that seals the water jacket, began leaking. Last year the crank shaft broke but I’m sure that is a rare occurrence, if not to only time that has ever happened, and it still ran to get him home. Fixed it and he used it this summer without any issues. This motor gets run a lot and aside from the broken crank, its been very reliable.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.