Maybe, but more than likely any CPU you buy will bottleneck 780's in SLI, depending on the resolution you are using. Overclocking will definitely help with performance, just make sure you have an aftermarket cooler and not the pos stock cooler.
Lower resolutions will shift the bottleneck to the processor, higher resolutions will shift the bottleneck towards the GPU.
The i7 2600k even though its older Sandy Bridge should not have an issue with bottlenecking. It is still a very powerful CPU. I have seen people run dual 770s/780s/7970s on the 3570k/4670k and have no bottlenecking. However, an OC would never hurt.