Warleech :
Nice build would last long i would go with 2 GPU and i loved your build you start making me thinking of buying the same perfect.
as Tiny voices said Get better RAMs, i would say go for higher than 1600mhz
It would be pointless to get 2 gtx760s. One 770 will max all current games and will for a long time. Then 2 years later you can add a second one when it starts to show its age.
With 2 gtx760's, you will have the problem with games that don't fully support SLI. You will be stuck with only one gtx760. This is the reason I am ditching my SLI setup in favor of a single card.