elenasgrumpy,
The trend these days is to severely overpower an airplane. This comes from the 3D flying that has become so popular lately. In 3D flying the plane needs to be overpower because the majority of flying is done with the wing in a stalled attitude. Because of this the motor/prop need to produce all of the lift needed to stay in the air. Also, in a lot of 3D maneuvers the only way out of the maneuver is to go straight up and pull out of it. They need the extra power the oversize engine produces.

With that in mind, for those of us that consider themselves to be average pilots (or sports pilots) don't really need that much power. A 60 size motor in this plane would be just fine for you. I would go ahead and use the motor you have, you'll be very happy with it.

Hope this helps

Ken