That's a very nice build.
Your set with your gpu. You can attempt to overclock it, but it should be fine at stock settings.
What are you using for a cpu cooler? I think you might get more fps with a better and stable overclock.
I'm also curious as to what games you're playing that getting below 60 fps.
As for the is it worth it question, I guess it depends on your situation. If you were starting with a brand new build and didn't already have a quality CPU, I'd say go for it. Keep in mind there are so few games and programs that take advantage of hyper-threading though. For a pure gaming machine, an unlocked i5 is usually the way to go and overclock the I5. That being said, it's your dime, and if you want to get an i7, go for it. They are very nice CPU's, are a little more future resistant than an i5, and I don't see how it could hurt anything other than your wallet.