That motor will definitely give you the performance you desire. As for the wing rocking is sounds nose heavy to me and like it does not have enough elev. on high rate to maintain a full stall. Wing rocking is primarily caused by the plane stalling, then picking up a little speed and trying to fly, then imediately stalling again. It does this over and over and everytime it stalls it causes the rocking to increase. Make sure you can get 40-45 degrees of elev. and then start adding some tailweight if that isn't enough.

Also do not hesitate to add a few click of throttle, the additional prop blast over the stab helps a lot.

Chip