I have a 360mm radiator in my roof but it wasn't easy and there are problems.
What ever radiator you buy it is not the length (ie 120, 240, 360, 480) that is the problem, it is the depth. A PA120.3 is hugely deep and if mounted in my cage would have hit the motherboard on its own without fans. I run a StealthGT 360mm radiator because it is the thinnest radiator I could find but the fans being the same depth again now encroach upon the motherboard so I had to trim the shroud and fan blades to miss the capacitors and stuff.
The major problem was caused by the fact I have a high end board (Striker II). If I'd bought a normal one my heatsinks would have been smaller and I'd of had less stuff cluttering the top.
So take the measurement of your motherboard for clearance then look at the space left over. I did mine with cardboard to check.