I have built 2 of them, and found that a .40 4-stroke is the perfect engine for that plane. First was powered by an OS .40 4-sroke, ~30 years ago. Second was powered by a Saito .40, a couple of years ago. Plenty of power, and it sounds cool, instead of like an angry bee (screaming 2-stroke).

With a Cub, you really need to fly the rudder in your turns. And that rudder is extremely effective. I caution you about doing snap rolls with a clipped wing Cub, as the SIG snap rolls are wicked and violent (kinda fun, too). It is difficult to stop the first one when you want it to stop (be high). And don't horse if off of the ground. It will tip stall.

Finally, land it on the main gear while it is still flying, and don't try a 3-point landing (especially if you have balloon wheels), as it will bounce like crazy.