The EVGA PowerLink has a spare connector inside the box, so it can be configured either in 6 & 8 pin or dual 8 pin with the small imbus key that's included. You should be fine. I used that PowerLink with my old Nvidia 980TI and now with the Vega7 on top of the pixlas mod. I do recommend it fully.
Got it installed, so far so good. It was really tricky fitting it into the Mac Pro due to the added length onto the video card plus the protruding wires, but I managed to get it in there.
One useful installation tip on JayzTwoCents was to remove both connectors and plug them into the video card separately, then slide them into the rail. Makes it easy to get a perfect fit and seat it flush against the video card.