Used to have a MK25 "rat" powerhead on a Quickie "H" mid/lower unit, and on a 9-1/2' flatbottom it'd do around 44mph. Found out later it was pretty sick, with busted rings. I fixed it up with new rings, hogged-out the case for a 50hp carb and it sounded pretty mean. Never got to run it on the boat again, someone broke into my garage & it was stolen. I was crushed to say the least, it was my favorite motor.
A few years back came across a good deal on a very clean 25SS and one of these days, got to take that out for a run. Hope it sounds as good as your 20H!
Wow Ed, hate a thief! Had a prize Trans Am stolen for the parking lot work, never seen again. On the lake when I was a kid, the guy next us had a 20H on a Hydro. My brother had a 20H on a Baby Switzer. Heres the only pic he could find of it. Miss those old innocent days at the lake and this kid amazed at what "fun on the water" is all about!