You should be fine with 240 mm rad on the bottom with slim fans. Btw what fans you will be using. I would reccomend noctua becouse they are best slim 120 fans on the market right now
It is the best riser cable on the market right now. Performance loss when using even the most powerfull cards is little to none. It has a bunch of engineering behind it and it is very high quality. It comes in wide range of sizes and PCIE conector placment, like type A,B,D etc. If it helps even...