A spot face would work for the set screw if you hit the same spot every time and it didn't get to mushrooming out to raise a spot on the shaft. The easiest way is a flat slightly wider than the face of the set screw. No need to mess with end on the set screw i.e. flattening or pointing. When your doing your pre-boating checkup, check these set screws they along with the clamp screws pinching the collar keep the drive off the key. Driving that key will create more stress than a keyway radius.