Understand, I have no personal experience with this sort of thing. The wife gve me the choice of a 10-22 or a CZ bolt for a retirement present, and I went with the bolt. (no regrets!)
On another forum, a replacement hammer kit is far and away the first choice for dropping the trigger pull. Some say that is all you need. (Well, that and LOTS of ammo.) Midway had 'em on sale some time ago.