I think the accuracy problems you've heard of relate to the time in which Ruger bought their barrels from many different outside sources. Some of the barrels were of poorer quality than others. Ruger for the last few years has made their own barrels and doesn't outsource them anymore. My Step-Dad has a MKI in 7MM Rem. Mag. out of the box with no tweaks this gun shoots Winchester Supreme ballistic Silver-tips under 3/4" of an inch. I say out of the box because he bought the rifle for a hunt that never materialized and it sat in the box for over 10 years without being fired. I put a Leupold scope on it for him and lined it up. The gun also shot Winchester 175 gr power points under 1". I fired these because this is the box of ammo he got when he purchased his rifle.

The one good point given by another response is that you will want to replace or have a gunsmith work on the trigger of a MKII. They are pretty horrible from the factory. I also have a cousin with a 7 Mag in a MKII. This is the most accurate factory rifle I have seen other than varmint weight small caliber rifles. His gun out of the box with Federal Premium 150 gr. Sierra Bt's was an honest 1/2" grouper. He loads his own and routinely shoots the 140 gr Barnes X in 1/2". I think you will do well with the Ruger.