The only real problem with the Ste. Marie Graphics NG receiver mount is that it's, by necessity, offset in relation to the bore axis. This gives it the same problem as the M1-C and D sniper rifles: at any range other than the "zero" point, POI will shift both horizontally and vertically.
While for plinking or target shooting at a fixed distance this would be less of an issue, it sure takes a lot more skill and practice to learn to use effectively when the exact range is unknown, as it most often is in most other situations.
IMO, the B-Square-type "Scout" mount would be a more practical choice for all around shooting. FWIW, the Swiss military "sniper" version of the K-31 had several substantive change from the standard issue model in order to mount a scope over the bore and facilitate loading and ejection.
Still, the K-31 action is unique, fascinating and it's quite possible that the entire supply of them are already in the surplus market. While the supplies of surplus GP-11 ammo are finite and rapidly dwindling, the supply of new reloadable boxer primed cases and factory ammo is better than it ever has been, and more likely to remain that way than not for a goodly while yet.
Dies and data are readily available and the cartridge uses standard sized primers, 0.308" dia. bullets and does very nicely with a variety of canister powders.
IMO, you won't see another opportunity to own such a finely made rifle as the K-31 for such a small price again in our lifetime, if ideed ever.
As has been mentioned, a Savage 110 will be able to be had inexpensively for a long, long while.
Unless you can only foresee being able to own one rifle for the rest of your life, get the nicest K-31 you can find now and a 110 of whatever sort you prefer at a later date. In 5-10 years (maybe less), you'll very likely be able to trade a nice K-31 even for a brand new Savage, IMO.
PS: tbs, I may be the most envious and depressed southpaw on the planet at the moment. The only other K-31 I ever saw with a set of diopter sights like that was a dedicated competition target rifle in .308 Win. at a big show in St. Louis several years ago. Righthanded, the asking price was almost $2000 and it was gone a couple of hours later when I went back to drool over it some more. It's gotta be five o'clock somewhere...