Your cpu will absolutely not bottleneck a 580, you've got a very nice overclock on it. Plan on getting my 1055T up to around 4 when i get a cooler that isn't stock >___<. As for your gpu dilemma, I just want to put in a suggestion, a 570. I was in your position a few months ago, looking for a great gpu for a reasonable price. I was looking at a 560ti, but it just didn't seem strong enough for what I wanted to do. Sure the clocks on it are amazingly high, but it lacks the physical hardware to back them up. My 570 at stock probably beats the 560ti overclocked versions by about 15 - 20%. I overclocked it a bit, as seen in my sig, and I'm getting nice frames on crysis 2, maxed out at 50. From what I read you ain't a fan of 50, but let me tell you, you will not notice much of a difference honestly. Maybe a bit from 50 to 60, but anything above that is either a) above your screen refresh rate anyway, so kinda pointless if you are going to use vysnc (from what I can tell you wouldn't like screen tearing so you would be the kinda guy to use it) or b) too expensive to maintain constantly.
560ti = around 250 bucks
570 = around 350 bucks
580 = around 500 bucks
The 570 is smack bang in the middle of these two, and in my opinion, offers the best price to performance ratio. Do a bit of googling and compare the physical hardware on both the 570 and the 580. They are pretty much like a 6950 and a 6970 in that the 570 is basically a *very slightly* downgraded 580. It has a little less VRAM (but I'm assuming you won't be using a res higher than 1080p or 1200p anyway, so kinda pointless), it has a slightly faster memory bus bandwidth, and slightly more cuda cores. So, basically the 580 is not that much of a jump from the 570 in terms of hardware, but a big jump in price. If you then wanted 580 like performance from a 570, get a good card with aftermarket cooling, pump up the volts and raise those clocks. I would think my sig card is close to a reference 580 in terms of performance, and I have obtained similar scores to those cards in 3d mark and the like.
Just a suggestion mate, it could help you save a bit of cash to put aside for another upgrade to kepler in the near future (if you wanted too). But by all means, if you want to spend the cash on it, grab a 580. You will definitely not be disappointed. I would specifically recommend an MSI lightning or the ASUS DCUII, great coolers on those two would allow you to get a nasty overclock on your gpu. Anyway, sorry for the tldr post, but good luck with your gpu hunting and more importantly, enjoy all that DX11 when you get it!
Edited by theSpacec0wboy - 8/4/11 at 2:46pm