I replaced the hammer and sear the other day. I still need to change out the trigger.
Not sure about the mag release. I did find this one interesting though.
http://i.ebayimg.com/t/USMC-Ruger-10-22-...MDk=/$%28KGrHqN,!oME63%28Z%29IiNBP!N-grWJw~~60_35.JPG