EKWB has announced that a number of its current water blocks are already compatible with the recently released GTX 760 (read our review here). According to EKWB, because the GTX 760 carries the same GK104 GPU found on the GTX 660 Ti, GTX 670, and GTX 680, a number of manufacturers have opted to use the PCBs from existing GTX 670 or GTX 680 parts. The water blocks for those cards will work on the set GTX 760 card accordingly.
While the use of various PCBs makes it difficult for users to choose which water block will work, it might be difficult for some to choose whether they need the EK-FC670 GTX or EK-FC680 GTX blocks, so EKWB has already added over 20 GTX 760 graphics cards to its configuration utility. Alternatively, you can always compare the PCB designs to figure out which cooler you need.
There is no word on whether EKWB is working on any water blocks specifically for the GTX 760.