...I also used that case (without the m.2 slot) for my build. Nevertheless, the Pi was getting quite hot very often despite the built-in fan and included thermal pads. Also, the fan is a little bit noisy above 50% of its maximum speed. I eventually moved my node from the Pi to a normal server....
Both of mine are running cool and the fan barely be heard. But, that's just my units.
...Let me tell you about another great solution. And if you're willing to spend a bit more and use an NVME M.2 drive, consider a RockPro64 SBC. It's way faster than Raspi4 and it supports the mentioned superfast drives....
Did you find / do you have a nice case that supports that card?
Everything I have seen is either big and expensive or looks like cheap plastic.
...note that the Pi CPU can be underclocked in /boot/config.txt.... somewhere, somehow 
...
...There is a line
#arm_freq= 700
With the above line commented out max by default is 1400, so if you uncomment it and put in a number lower then 1400 is will never go above that.
-Dave