The only "major" upgrades I have ever done to any of my MKIIs has been trigger work. I have used my 5.5" MKII in bullseye matches where one hand shooting is required and for me , the stock trigger just did not cut it.
I also had the 5.5" drilled and tapped and added the Ruger scope base. Also have a set of Nill target grips.
I also had the 5.5" drilled and tapped and added the Ruger scope base. Also have a set of Nill target grips.