Hi Cafeenman! I hope you do build one and show us the results. I think the .61 FX sounds best. This bipe can be finished around 7 lbs. The ST .75 seemed very powerful here at 6300 ft. so the .61 should be similar where you are. A 14 inch prop clips a bit of grass now and then. The twin sounds better for a Goldberg Ultimate. I'm talking about "traditional aerobatics", not 3D unlimited vertical etc. Maybe the 1.08 would power the Superhog. The concensus from what I've heard and read is .91 4-stroke power's the best.