will sli 770 2GB cards be able to run games on ultra on a 1440p monitor?
Oh, yes. Hell, one 770 will run pretty much anything at medium/high and 1440p.
Just don't get the 4GB version. The card can't take advantage of all the VRAM due to the bus. Personally, I'd get a 280X, it has 3GB of VRAM and can actually use it. Plus, it trades bliws pretty well with the 770.