IMO a "Cub" begs for a 4-stroke engine. I built one once with a 2 stroke and never had good luck with it. The tank was too high for the engine and it tended to quit on the approach when throttled down. But, aside from that, the sound and scale performance with the 4 stroke really adds realism and class to the "Cub". Go for the the 4.

DaveB