The Seagull Super Star performs very well with a 1.20 two stroke GMS. We have three of them at our club and all are well liked. That would be roughly the same power as a 180 Saito and quite a bit more than the G26. The OS 120AX would be another good choice. Stay away from the gas engines, they are just too heavy for that airplane. The Super Star will weigh 10 pounds with the 1.20 two stroke. When they get heavier than that, they get "tip-stally"

The best advice I can give you is to limit the elevator travel to less than 1/2" each way. More than that and full deflection will give you an instant snap-roll.

Jim