Pretty creative design. Definitely lots of thought about the layout from someone who does WC. I don't see a problem with a bigger case for WC since WC parts multiply like rabbits as the components being cooled increase in performance.

How much air intake do you have? It seems to have a ton of exhaust but little intake. My custom design(s) normally have 1 or 2 more exhaust fans than intake (currently planned rig is going to have 4 intake and 5 exhaust + PSU fan). Just a thought.