I've loaded the 7.62x39 with various bullets up to 154gr. You will get good results with them, but I found that the .308 bullets worked just as well or a bit better than the .311-.312".
I've had three different SKS's, and all shot best with the Nosler 125gr Ballistic Tip. I mostly used AA1680, but IMR3031, H322, H335 all worked well too.
I would suggest using the Remington 125gr Soft Points (.308") available in bulk for general use, and the Nosler Ballistic tip for accuracy, and longer range hunting.
The problem with using the heavier .303 bullets is that they are constructed for the velocities of the .303 Brit., and other 7.65mm firearms, and as such may not adequately expand given the reduced muzzle velocity of 150gr bullets in the 7.62x39 (~2,000 to 2,100fps, depending on barrel length).
However, I had superlative results with the 155gr Pt.GC Lee bullet mould and H4227 for around 1,900fps. This bullet cast soft would modestly expand on deer if bones were hit, and performed satisfactorily.
Ruger made a run of m77mkII's back in the late '80's to early '90's, and ones I saw were Stainless Steel w/synthetic stocks. Accuracy with good reloads was at or under 1" at 100yds. I believe they used the same .308bore and tapered throat of the Mini-30's.
CZ and Charles Daly are importing small action b/a's in 7.62x39. The Mini-MkX was available back in late '80's. It's now back as the Charles Daly Mini-Mauser.
If you get one of the b/a's and later get "tired" of the 7.62x39, It's a relatively easy swap of barrels to get a 6mm PPC. (uses same size bolt face) Most of these I've seen/shot, even with light sporter barrels would shoot to around 0.25" at 100yds!
One of my next projects!