I'm running an i5 760i@ 3.4GHz (Overclocked from Stock 2.8GHz). I was considering upgrading to the i5-2500k but decided against it ever since having overclocked to 3.4. Its been performing great so far! No issues whatsoever! In the past, I've coupled it with a GTS250, GTX470 and now GTX670 and its been more than satisfactory for me. Mind, the GPU makes a lot of difference.
Before getting the 670, I ran the i5 on many of the demanding titles like GTA4, BF3, COD:MW series, Max Payne 3, etc. The quad core was more than sufficient for them all. Your GPU is pretty decent and will manage most titles at high-highest settings.
The i5-760 is a very good chip and can easily be overclocked, though like the member above said, not as easily as the sandy bridge series. But it's doable nonetheless. I've read reviews where people have managed to OC the 760 upto 4GHZ. But many had problems at those speeds. Having failed at 4 GHZ, a lot of people have managed to stick to 3.8 however, for those clocks, you'll need to get a decent CPU cooler as the one provided by intel just doesn't cut it.
Overclocking actually depends from case to case. While one user might have no problems with 3.8, another might find it hard to achieve even 3.6. Me for instance, I touched 3.6 but the system would get buggy and lock up. 3.5 faired pretty well and seemed stable for a good while. Being overcautious, I settled in on 3.4GHz, which is pretty much good enough for me.
So yeah, the 760 is a good quad-core chip for gaming! If you're not happy with the stock speeds, you can always OC it to whatever speed best suits your setup. As I said, the GPU+CPU combo makes a load of difference. I would recommend that you save up on the cash and buy a better GPU (6870 for eg). That coupled with the 760 would give you a pretty decent rig!