[Cvans]

I't OK to use a wire brush on the head of the piston but not on the sides. You'll remove too much aluminum. Make sure that there is not carbon under the piston rings.
As far as your dented pulley goes, cut a piece of hardwood (oak or maple) in the shape of a splitting wedge so that it fits tight in an undamaged area of the pulley. Go to the damaged area and lightly drive the wedge in. With a brass hammer tap in on either side of the dent until the lip of the pulley is straight again. It doesn't have to be perfect. Belts are somewhat forgiving as long as there are no burrs or sharp edges.