It will fit just fine into the correct slot without any issues. Supporting the weight of the card is another issue. You could always tie it off from the top of your case or support it some other way but the AMP! Extreme would also be my choice. I would definitely make sure that the PCB is supported though.
There is no "correct" slot in that sense. Any 16x or 8X slot will work (aka those grey slots for you). It does look like the Black and Grey slots (2rd and 3rd) are eclectically pinned at 8x, but that will not make any difference. No card tapes out 8X PCIE 3.0 yet. The new Titan might be very close, but nothing else will. The motherboard does not care and with practically every board for the last few generations "Auto" selects the correct slot. Years ago you have to select the primary PCIE slot, but thats long gone since "Auto" option does the job. I personally have my GTX 1070 in the 3rd slot on my X99 and the the 2nd 16x pcie on my x79. Not forgetting the second slot on my z97 build with a GX 960. Yes I have a lot of computers.
Also the reason why I said slot one is not a good idea, I have shorted out a video card when the back touched a CPU cooler before. Not my best judgement at the time, I thought its close but it's not touching. Well...it arc and took out the video card about an hour into use. So It will be very close. Now the Zotic has a back plate so chances are you won't short anything, but I've seen stranger things happen. Just keep an eye out for the CPU