I'm modding an SX1240 right now. My rad. is 11x6x2. I am having a little trouble getting things placed right though. I would like them to fit a little better.. With my setup I probably wouldn't be able to put any drives in the top two bays because the rad/fans will be in the way, and I'm going to have the tubes go into the rad. above the PSU. It's really the best way I think I can get it in. I'm getting to the point where I just want to get it finished so I can get my new computer up and running.
Oh, and if it's 6" wide, it will just barely fit between the walls for the 5 1/4 bays, so you don't need to cut them up, it is just long enough so that you can't put a drive in the bay.