A Cocker or Mag grip will fit with some work. Look over at PGPOGs websight. I don't think there are any other bolts that will fit, I can't believe the hammer would be shot. It's a pretty substantial piece of steel and polishing it would probably make it all right as long as the sear notch isn't ruined.
Here is the site addy; http://pgpog.org/cgi-bin/yabb/YaBB.cgi
There is a very informative page also if you hit the "home" button at the top of the page. Good luck.