This isn't going to happen. At least, not in the way you're thinking.
The R9 Fury X runs incredibly hot. That's WHY there's a watercooler on it, and that's why the radiator is so much thicker than any other AIO-cooled GPU ever made. Putting an air cooler on it would simply not be a good idea.
Want proof? Just look at the R9 Nano. It's essentially exactly the same as a Fury X, it actually runs a bit cooler due to different power delivery, and it has the kind of cooler you're looking to mod into your card, with a 90mm fan. But oh no, the R9 Nano thermal throttles like a serial killer with swine flu. The only way to get proper performance out of an R9 Nano is to watercool it. Which is what AMD did already. With the Fury X.
The only kind of air cooler you'd want to put on an R9 Fury X would be something like a Raijintek Morpheus II. It's universally compatible with modern GPUs, so all you need to do is make sure you stick enough mini-heatsinks to the power delivery VRMs that they won't fry.
You're an absolute lunatic, of course they are. The entire inside of the card is covered in a MASSIVE aluminium plate covering all the VRMs and power delivery. There are cooling pads on the important parts. Do NOT run that card without cooling on the important PCB components.
The only drawback is that the Morpheus is fucking gigantic. So it's probably not what you're looking for.
The best option, if you absolutely can't use the AIO cooler on your card for some reason, might honestly be to sell the Fury X and buy an R9 Nano instead. If you have a high-airflow case you might not run into any throttling.
Actually, screw that- if you're selling your R9 Fury X, replace it with a 1070 Mini from Gigabyte. It performs MUCH better than the R9 Nano in exactly the same form factor.
TL;DR Fury X can't survive without water, find a way to live with its cooler or get one of these.