If I understand what you are saying correctly, yes, jack up the engine and replace the motor mounts. What's the West System part of it? Is there damage to the glassed stringers or is the damage to the iron that the engine mounts are bolted to?? Also don't forget that the shaft and engine has to be realigned after the new mounts are installed. For that much damage you should also check the shaft, shaft log, cutless bearing and strut. Dang!! Takes a lot of force to do all that!!