How about this. I have a Saito 65 in mine with a 11x6 prop and it leaps off the ground after about a 15 foot roll. Will fly all day at half throttle. Have gone as long as 45 minutes nonstop with a 16 oz. tank. Now for the best part. If BlueMax3 wants to move up to a bigger engine the Saito 80 and 91 has the exact same mounting dimensions as the 65. The 72 is different,smaller, so it would mean changing out the engine mount and drilling new mount holes etc. Just start with the 65 and later if the situation asks for more engine just drop the 80 or 91 right into it. Jm2cents