OK so here is what my friends at evga tell me.
1. The FE waterblock will fit... eK's will, however, you need to mod the card slightly.
You need to physically remove a fan header, to make the block sit flush.
2. The eVGA waterblock would fit as well without mods.
It lists the hydro version as compatiable, and my friend again said, the hydro AIO version is the same pcb as the air cooled one, so if one fits the other should.
However good luck finding the evga block.
I have spent about 20 min looking for it, and well, sigh.... no luck
This is what you want if you can find it:
https://www.evga.com/support/manuals/files/400-HC-5599-B1_manual.pdf
which is the same block shown here:
https://www.amazon.ca/EVGA-GeForce-GAMING-GDDR5X-Technology/dp/B073GYYBHJ/ref=sr_1_1?ie=UTF8&qid=1515793968&sr=8-1&keywords=EVGA+1080+Ti&th=1
The waterblock is the normal FE design.
Evga only had 2 designs.. one was FE, the other was FTW3.
Ignoring the Kingpin one, because well, i heard less then 100 was made for that one, as you got the card to LN2 and not watercool.
My friend also says you MIGHT try and get lucky with calling eVGA and asking if they have one in the back not listed on there site.