I have knurled the armature shaft on a few generators to hold the new bearing tight, where the old bearing had worn the shaft. The C lock rings are soft steel and will stay where you bend them, so they are fairly easy to remove and replace, but be sure to squeeze them tight and round when you reinstall them. Pay attention to all the parts on the front as you drill the 4 rivets and take it apart. I've seen where someone has left the spacer out and this leads to excess endplay and other problems. Rivet/nuts are easy to use instead of true rivets, when you replace the bearing and retainer plate.
Use a drill bit to remove the rolled lip on the rivets, and you'll have to hold it at an angle if the armature is still installed, so don't let the bit slip and catch the armature windings.
Use a replacement bolt to hammer on to remove the pulley. Just tighten the bolt and hit it with a hammer while you hold the pulley in your other hand.