For gaming, hyperthreading of the 3770 is not much help.
Few games use more than 2-3 cores.
A 3570 would be equally good.
Considering the easy 20% cpu boost from overclocking, I would buy a "K". Preserve that option.
A 4670K will cost less than a 3770 and perform better even at stock.
That said, I would consider haswell which will be in the same price range.
You will get a superior Z87 chipset motherboard.
To get some idea if you would do better with a cpu or gpu upgrade,
run these two tests:
a) Run your games, but lower your resolution and eye candy.
If your FPS increases, it indicates that your cpu is strong enough to drive a better graphics configuration.
If your FPS stays the same, you are likely more cpu limited.
b) Limit your cpu, either by reducing the OC, or, in windows power management, limit the maximum cpu% to something like 50%.
This will simulate what a lack of cpu power will do.
And... I would highly recommend a ssd for the os.
120gb will hold the os and a handful of games.
Go to control panel/power options/change plan settings/change advanced power settings/processor power management/maximum processor state/
set to 50% and see how you do.
If your FPS drops significantly, it is an indicator that your cpu is the limiting factor, and a cpu upgrade is in order.
It is possible that both tests are positive, indicating that you have a well balanced system, and both cpu and gpu need to be upgraded to get better gaming FPS.