The best (inexpensive) 7.62x39 bolt guns out there are the many small-ring Mausers with a little conversion work.
Both the 7mm and the 7.62 Nato barrels are pretty happy with the SKS rounds. All they need are chamber adapters which are available (so much more than) reasonably from MCA Sports. I've done each of them over the years, and my main 'truck gun' is still a 7.62 Spanish with a chamber adapter. It shoots about 3" at 100 yds from a vise, about 7" off hand, which is good enough for me. It only hits about four inches lower than the .308 Win from the same gun before the conversion, but *feels* much safer out of the old action.
Yes, there are commercial guns available, but an old Mauser with a little work (and maybe a Timney trigger) will take you a long ways.