I had a “below the decks” inboard motor based on the Sachs powerhead — 1 rotor, can’t remember the carb manufacturer.
Gawd-awful heavy and hard on fuel, but very smooth and quiet.
It was installed the center of a self-propelled surf-board — was heavy enough to keep the center-of-gravity low enough so I wouldn’t tip it over.
I think the top RPM was around 4,000. Slower than a 2-stroke 2-cylinder to accellerate, but had good torque.