Don't get the 8320. Period.
The 8350 doesn't perform as well as the 4670K, but the differences in **GAMING PERFORMANCE** are so small, that the 8350 is easily the better deal. If I was in your position, I would get the 8350 just for the simple fact that it's cheaper (unless the price went up, don't know).
Also, no matter which one you get, don't use the stock cooler.... especially with the 8350.
Hope this helps