Sounds like you've got a handle on the barrel swap. I have to go with drop-ins as I'm no gunsmith! I usually buy the Jarvis or KKM drop-ins and have good success with them. I have a mdl 17 that will shoot 3" or a little bit less at 25yds on a good day. This one still has the Glock barrel. I concentrated on the trigger mechanism to improve accuracy on mine. I installed the Wolff 4# firing pin spring, the factory 3.5# connector and 4# trigger spring, the Ultimate Trigger Stop from Lone Wolf, and polished all the bearing surfaces. Great improvement to the trigger pull. Makes it much easier to shoot well. Good luck with your 22, let us know how it turns out.
Savage