Ohh you mean a 120x2 sized rad. Or a MCR 220 Or an XSPC RX240. Or a Black Ice 240 SR-1.

Look in the mods section at the top of this forum, you'll get LOTS of ideas.

Many just mount it off the back of the case. Don't limit your rad size because it has to fit, you have to overcome physics first, ie enough cooling.