I have built and tested this thing u asking myself, and best cooling you will get by placing rads on the front (intake). Because intake air will be much cooler than inside the case. Place it front, you wont regret becausr there is no cons at all. Ofc make sure u place exhaust fans to draw all the heat from other components, like ram and mobo etc.
PS, Is it your computer? looks sexy
Cool, Yeah that's what I was thinking. Probably just leave 140mm fan there and move the rad to the front.
And yeah it is, Here's another pic with it onhttp://imagizer.imageshack.us/v2/800x600q90/923/aPHCXx.jpg