I believe that AM430 Michigan wheel ( 291707185374) would be good. Raising the motor should help keep down the water over the transom. If it runs faster than 4500 RPM the prop should be "Cupped". This is what they call curling the trailing edce on the blades. This has the effect of increasing the pitch. A good prop man could fix it. You must be careful to do an even curve and the exact same modification on all blades. I used a 1-⅞" trailer hitch ball and a raw hide hammer . . . 😀

A word of caution- That Michigan wheel being brass is heavier than the factory aluminum so it will exert more force on the mechanism when shifting. There is no synchromesh in the dog clutch used in outboards. It is eather in or out. There is 30 degrees of free play between the dogs. It is during this time that he dogs will snap in full contact. At a slow idle the is still measured in meliseconds. It is important the motor be running slow and that it is snapped quickly into gear. When the motor is stopped in neutral, there is a chance the dogs will line up so it is impossible to shift into gear. In this case just turn the propeller so the dogs line up with spaces.

This prop is meant for the 9.5 and 10hp, won’t fit on the 7.5hp and is too much pitch for it….

Well, not quite…The 5.5/7.5 uses a different style of propeller and drive pin location than the 1958 and newer 9.5/10hp models. The 50s model 5.5/7.5s use a solid prop (no rubber hub) with a drive pin near the outer end of the prop shaft, there is a rubber cap that snaps in place over the drive and cotter pins….The early 6hp models used this same style prop…
The 1958 and newer 9.5/10hps (along with later model 6hps) used a propeller with a rubber hub and a drive pin located right near the prop shaft seal, the prop shaft is threaded on the outer end to receive and plastic threaded cap and cotter pin.
So, I would say that propco’s grouping of a single propeller style from 1954-1981 is a mistake.
And yes, the 5.5/7.5 models used the same style prop shaft/prop setup with different pitch props. The early 6hp models used this same setup, the later models used the same setup as found on the 1958 and newer 9.5-10hp models, just different pitch props.
I will look on the propco website, perhaps I can get a better idea of what is needed for your engine…

OK, I looked at the Propco website. I don’t understand how one hub can be made to fit the two different style setups, you should contact Propco, perhaps it is some of universal hub that can be made to fit both styles….