CPU Upgrade Help

Alright so I am stuck on whether to get the AMD 8150 (8 core zambezi), or 6300 (6 core-New FX Series). On the CPU benchmarks lists I notice that the 8 core 8150 is easily the highest (and I can get this for 160 on newegg currently). But I do not need my CPU for multitasking (usually best with 8 cores) , I want my CPU to be the best for gaming. I also read somewhere that the 6300 is not 6 true cores but is 3 cores and hyperthreaded, not sure if its true but still. I think if I go with the 6300 and use that extra money to get a good aftermarket heatsink, I can overclock to get to around what an i5 would be. Again this will be mainly for gaming not multitasking. My motherboard is the the ASrock 970 Extreme 3, and my video card is the GTX 660 if giving this information helps with anything.

Edit: My current CPU is an i3 2100 dual core. Will I see a difference in gaming with any of these CPU's?

Any feedback is appreciated.
-Thanks