The 2 top fans obviously would go in the upper compartment to save space , 75 mm more or less under the compartment would start getting awfully close to your mobo , I tried to link the updated diagram but dont know if it worked , just writes a url .. and you need the same size fans because otherwise air will be lost going around the rad and there will be less pressure because with the proper sized fans , the air is stuck in the fan shroud before being pushed through the rad and then sucked into the next fan shroud , imagine using water , you lose water over the sides and obviously less pressure going through it !
Guess I could still throw up some photos just to give an end result to how it's finally turned out.
