I wouldn't go past an FX 8350 speed on a 8320 with that board, and even that might be pushing your luck. I would just get a decent cooler an bump the FX 6300 to FX 6350 speeds. Despite the TDP rating, there is no way an FX 6350 uses the same amount of power than an FX 8320/8350.
Just save your money, get a decent cooler, and set your multiplier to 20. That will give you FX 8350 clock speed while using far less power. Also, depending on the game you are trying to play, an FX 8320 may do nothing for you. Not many games can take advantage of more than 2-4 threads.
Just keep your money and stay with the 6300 for now. An 8320 isn't enough of an upgrade to be worth what you're spending, at least for gaming.
^This. Like I said earlier, a decent cooler and a small overclock are better for the $$$. Multiplier @ 19.5 gives you an FX 6350 speed of 3.9ghz. A 20 will give 4.0. I wouldn't go any higher than that, though.