Re: 80’s/90’s 50hp opinions?

[Don]

You can’t put the larger gearcase on the 40/50hp exhaust housing. The 55hp is not a different powerhead, just some minor port differences. The 45/55hp engines will be tough to find used, not many sold, and probably worn out if they were actually used commercially.
In other words, if the 50hp is in good shape, and priced reasonably, buy it! Don’t wait for the elusive commercial model to show up. You could always resell the 50hp if you find a 45/55hp at a later date. Keep in mind that many of those commercial engines are recoil start, so there would be a big expense converting them to remote electric.