You already upgraded? What did ya replace your 760 with?
I'm pretty sure whatever I upgrade to is going to have to be above a 770 since If I'm not mistaken, a 770 is only ~15% stronger than a 760, is this correct?
800 series should hopefully be out somewhere around the same time as the game is released. So if you get the 870 you will most likely see a big boost.
No use in upgrading from your 760 since the small gain you get with 770 isn't worth it and the price for anything above that really isn't worth that upgrade now unless you really need the power right now (120Hz or higher res).