CyborgCity has the right idea, of course, if you have the cash for dual GTX 760's, why not get something like a single gtx 770 or r9 280x which will offer the option of SLI at a later date. GTX 760 can run most games maxed out nowadays but sooner or later it's performance will not be able to handle games whereas a 770 will prolong the time where it can support modern games.
(Sorry that last sentence sounded a bit confusing).