For me the MK II was the high water mark of the Ruger MK series. It does not have the loaded chamber indicator, nor magazine disconnect that the MK III has, which at times can at the least me a nuisance, and at the most be problematic to function. The good news is that you can remove the LCI, and mag disconnect with a few aftermarket parts, and a little of your or a gunsmith's time. The alternative is just finding a nice used MK II.
I have the Mark III. Can you explain why you would want to change the loaded chamber indicator and magazine disconnect? I'm not sure I understand the advantage of modifying the pistol.
I have only shot about 1,000 rounds through it as it is a new pistol. My only other experience with a .22 pistol was a Colt Woodsman Match Target - so, I have no other comparison for understanding what difference the changes would make in the Mark III.