In reality, they're fairly close. If the FX-6300 had a bigger cache and more threads, it might be different. This i7 doesn't have the same performance characteristics of current generation i7's. Depending on the price you can get that for, it might be more worth your while to find an FX-6350, with a faster clock speed and more cache than the 6300. Really I'd recommend going with any i5 Haswell refresh chip. Even a current generation i3 completely kicks the shit out of the 6300, 6350, i7-960 or any of the other FX chips INCLUDING the 8 core chips.
It's also completely worthwhile as a gaming processor. As you can see here it puts up almost identical number to the i5, for less money.
http://www.techspot.com/review/943-best-value-desktop-cpu/page6.html
What is your actual budget for the entire build and what do you already have?