You wont know until you try I suppose. What's preventing you from buying the cards, testing them in the StormTrooper, and if it doesn't work to your satifsaction, get something like, a Carbide 500, 650D, or a Fortress FT02, or whatever is suppose to have better cooling performance.
Secondly, I'd always very carefully consider the need for multiple GPUs. They need good airflow / watercooling (heance a new case, which I'm not sure you need), they need more power, your available VRAM doesn't scale up, and some games don't like SLI / Crossfire that much, although nowadays they seem to be more rare.