I would never run Hitec HS55 or any HS-80,81,82 or 85s with plastic gears... MJD is spot on for the servos. Those Hitec HS-65HB are the best small servos out there. very very strong gear train, light weight and no slop over time. Of those three engines I say the AP then TT then black widow. Run the APC 6x4 1/2A prop. it is a big load for it but pulls large planes very well and is about 19 ounces of thrust in a plane.