Unless you have already bought the 200mm rad, drop that idea.
I got 480mm Rad space and I am cooling 2 OC'd Graphics cards and a OC'd CPU from those with no problem. see my sig for pictures.
In your case, I would have a 240 rad in the top exhausting upwards, and then mod the bottomn of the 650D and fit a 240 down there exhausting downwards. and then mount the HDD's in the Drive bays with adapters
The yellow circle is the pump, and you dont have a res, but only a fill tube with a Y so that the water from the top rad can get back to the pump.
I believe this would be the best solution
, though it requires you to dremel out holes in the bottomn of the 650D, but that is easy