The MK II and MK III uppers for both the 22/45 and the regular models are exactly the same except for one small issue ... the loaded chamber indicator. There are two options. You can either modify the MK II bolt face with a slot for the LCI or you can remove the LCI completely from the MK III upper. If you choose to cut a slot in your MK II bolt, it will work just fine with both uppers.
I can do the swap for you, and teach you to do it at the same time if you purchase the upper. I do not have the ability currently to machine the bolt, but i can remove the loaded chamber indicator.
But, we don't know about the Mark I frame and the Upper does not include the bolt, right?
I had thought you were selling everything north of the grip frame.
You mention gently used twice... but what is the round count? And to keep this convo short and not string out all the questions....
What kind of ammo did you shoot through it?
What rate of fire did you shoot?
What did you use to clean the inside of the barrel?
What did you use to clean the outside of the barrel?
Did you only use factory ammo, or did you reload for this .22lr?