The 760 currently struggles a bit with Crysis 3 at max settings @ 1080p with frequent dips down into the 20/30 FPS range.
The 760 is a much weaker card compared to the 770/780 or the 280/290 from AMD.
You would likely see a 20% - 30% gain going from your 6950 to a 760. Whereas a jump to the 770 would be around a 45% jump.
Thanks for the help!