I doubt it would fit a 360mm rad without some modding.
At a min, if you removed the thre internal fans at the front, you might be able to install a 360mm rad in their place (if the rad was not too thick), but you'd still need to mount the fans, and there is no room on the inside for the bottom fan because of the hdd compartment, and there will be no room for the middle fan if you have a long video card.
That then leaves you with the need to mount them on the ouside on the front panel behind the alu facia - but that will require some modding to remove the air filter assembly that is there. You'll also need low profile fans for them to fit.
Also, once the fans are installed, you'll need to ensure the fans have unhindered access to fresh air - so if there is not enough clearance to the front alu facia, you'll either have to mod how the facia mounts so it has more room, or you'll need to drill/cut holes for air to pass through.
Saying that, AFAIK, a 240mm rad fits their in place of the top two fans without modding - so long as your gfx card is not too long.
I don't understand why most of the people that have posted in this thread have failed to answer the OP's questions.
To the OP, if you are content with mounting an external radiator than you may be able to mount one on the top and have it hang off. I believe Badfastbussa has made a mod like that to one of his cases. Using risers, he elevated the radiator some 2-3 inches to allow for airflow under the radiator.
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