If you did not own a pc I would always advise going intel quad for gaming, but as you own the reasonably capable 6300 I would say get the games and see if anything is laggy. I suspect with the right settings you will be happy and can upgrade in another year or so.
A reason I want to upgrade is because I get alot of lag spikes on Watch_Dogs and run DayZ at 20-30 fps...
You'll need at least $350 to go Intel you have to get a mobo and cpu. You'll get a lot more bang for your money by selling the 760 and getting a 770 or 780.
Check Tomshardware test of the upcoming G3258. Most of the games are not that cpu bottle necked. Tea you are making the assumption that the cpu is the bottle neck.