Hey Weatherman, just buy the 3w-75us from from Aircraft-international. I think they are about $550 and it will have more than enough power for your application. the setup is easier because you dont have to have the carberator in the motor box. That can get sloppy and hard to get at to tune.

My 3w-75us is on my Carden 30% cap. weight 20lbs. More than enough power. Pulls a Mezjlik 26-10 at 6100.