I'm finishing up a UFO for which I bought two 3151s and two 3152s. I will use the 3151s for the ailerons and the 3152s for rudder and elevator. I'll be using a 5-cell 6v rx pack and I'm certain these servos will be adequate for a 7 1/4lb plane (54 oz-in and 87 oz-in respectively). Your plane sounds like it's around the 8lb or less range, so I think these are fine. It really just comes down to how much you are willing to invest in an r/c model.