Reminds me of the CMB I had in my Hydroplane. It was similar to this:
2.8 HP / 35,000 RPM
Bore: 16.33 mm
Stroke: 16.7 mm
Displacement: 3.49 cc
To put the output into perspective, if a cleveland made the same power per litre, you would be looking at around 4630hp.
My engine was ported and had an exhaust throttle. Used to run on around 50% nitro, so made a bit more power than a stock motor.