I met a guy at the range once and he had a 12ish inch 7.63X39 barrel. In fact, I shot it. I thought to myself, "hey, I need to get one of those". Shortly thereafter I thought...."WHY?". I already have a 30-30 barrel which is probably better and definitely more versatile.
I'd opt for a 30-30 hands down but if you already shoot the 7.62 round in a rifle or something, then it might be worth considering.