tiny voices :
The cheapest i5 you can get. You can usually get used Sandy Bridge i5s for like $120 on Amazon.
I wouldn't worry about SLi down the road, honestly. As far as the whole planning your system for "future" upgrades, I'd watch this video, you'll learn a lot. But yea, systems typically are going to be more cost effective for performance just to rebuild every 3-4 years vs upgrading them. And yea, a SB or Ivy i5 will be fine to pair with a GTX 760. I really would stay away from the lower tier Sandy's though (i5-23xx), those are bastard children of the Sandy Bridge line, my OC'd Phenom II 975 beats them on Cinebench, they're just clocked too low and you cant overclock them. Go with i5-2400 or higher if going with Sandy Bridges.
thx a bunch exact answer I wanted I would give you best answer but error 404 keeps coming up but ill still try to give that to you
Video-
https://www.youtube.com/watch?v=FK4ip08auGg