No way. You will need a second GTX 770 to do anything with two 4K displays. The GTX 770 was just designed to push 1080P.
Even GPUs like the GTX 780ti will struggle to run dual 4K displays at a good framerate, as they are designed just to run 1440p on ultra or one 4K display. With the R295x2 you could, but the GTX 770 is no-where near that standard.
If I were you instead of getting two 4K displays sell your 770 and get a R9 290X or buy a second 770. Only then will you be able to run ONE 4K display with good framerate.
Hope I helped ;D