|"i still need the fans because its not a case you buy in stores"|
Please read what I wrote in my last response: a properly designed case only needs one exhaust fan in the rear.
I have no idea what it is you're doing, but if you actually need 4 huge fans to keep it cool, you're probably doing something wrong. Don't be fooled by the so-called "gamer cases" that have fans all over the place, they were designed for suckers.
I used to work in HVAC (over 15 yrs in design, fabrication, installation) & to me, a computer case is similar to a small building. All you need to do is calculate the size of the case & decide how often all the air within that case needs to be removed & replaced, then you can choose a fan (or fans). As a rough guess, the average computer case is approx 1.5' x 1.'5 x 0.75' which works out to 1.6875 cubic feet (CF). For easy math, round it up to 2.0 CF. Using the info you provided, a single 200mm fan is rated at 47.4 CFM (call it 48 CFM). That means that in just one minute, that single fan will refresh the air inside the 24 times, in other words, every 2.5 seconds. Do you really think you need more than that?