The YS 53 would be a good match for the 80" Cub. I have an 80" Cub that I fly with a Magnum 52 four stroke, and flight is very scale with that engine. The YS would give you more power if needed, but allow scale flying at half throttle or less.

The 53 would also be a good engine in pretty much any 40 size sport plane, and many of the lighter scale 40 size.
Dennis-