Update!
I got the cooler installed today and its finally done
The 2mm gap issue was resolved pretty easily, I discovered that the plastic spacers from the Secufirm 2+ kit differ in height, specifically the LGA1200/115x spacers (Black) are about a millimeter thicker than the ones you are supposed to use for LGA 1700 (Blue)
So I used the LGA1200 ones instead, the remaining 1mm of thickness I stuck foam stickers below the NM-SFB4 bracket and that combination makes the bracket to IHS distance the same as Noctua's coolers.
Obviously this is a hack and won't work if I was to upgrade to an AM5 system in the future or something but its perfect right now and the mounting pressure feels quite adequate, no different to how I remember installing an NH-D15 or U9S that I used to have.
Previously I mentioned that getting a 30mm thick fan might be better but after installation I think its not a good idea because its hard to reach the bracket screws with the fan in the way. With this 25mm thick fan its just out of the way to screw in the cooler without any risk of stripping. Here's the angle the screwdriver needs to go in to get to the bracket.
The screwdriver makes contact with the fan blades and the fan has to be rotated to a specific position to get the screwdriver straighter. There's no issue with tightening it though and other than this detail the install went very smoothly.
Here it is finally installed and a close up of the mounting hardware
Here it is running in all its glory:
The cooler actually works surprisingly well for something that's so old. My unscientific guess is it performs similarly to a modern higher end 120mm cooler.
Here's a quick test of temps using CPU-Z stress test. Its keeping the cpu at around
~69°c @ 140w
I want to do proper power testing and see how much power it can handle but no promises for the time being.
Anyways, this has been pretty successful, I absolutely love it, and it looks and runs amazing!
I'm gonna go stare at it some more, thanks for reading!