I'm trying to clear out a lot of engines I will never use, but what's an engine nut to do? I couldn't resist having an example of a classic stunt engine, and have just purchased one of Bristunt's ABC set-ups for my last Max-S35. It dropped in perfectly, and if I ever have time, that Stunt Machine looks like a real contender.
The Max-III 35 is a much heavier engine, with integral steel fins, held to the c/case by only two screws, fore and aft. They are excellent powerful motors, but a bit wild for stunt. The earlier Max-I and II 35's were also good stunt motors. Agree the other comments on Max-S 30 and 35. In England I think we would say "more powerful" rather than "stronger". For our usage we could e.g. confuse stronger as meaning less liable to damage in a crash.