I was lucky, I guess
When I did mine it was a straight swap of the old parts to the new ones in the kit I bought from Catalina Direct. The hole in the keel didn't show any major elongation but the pin did show some wear and I therefore didn't need to worry about a bushing, sleeve, etc. Also, I had no trouble with the removal of the bolts after I gave them several shots of rust penetrating "stuff" (I think I used PB Blaster, but most any brand will help loosen things up--just be sure to give it several shots over a couple of days if possible). The pin just slips in--no threads--as described by the previous poster. I can't remember the torque settings recommended for tightening the new hanging bolts but you should be sure to torque it to the recommended specs to avoid breaking off a bolt. Be careful to distribute the jacking loads when lifting the boat by using large/thick pieces of wood between the jack and the hull. Go slowly and watch for hull distortion. Relocate the lifting point a bit if necessary to find a solid lift point. Also, make sure you do this as at least a "two man job" so you have someone watching for potentially dangerous shifts, etc. Good luck!