My rad is a EK CoolStream PE 360, it's 38mm thick.
You won't need 2 loops or even 2 kits, later down the track, if you wish to watercool the gpu too, you can just buy the block and another rad (plus fittings) and add them to the existing loop, the single pump is plenty powerful enough to handle that.
I would grab a tape measure or something to measure the clearance for the gpu.
The site doesn't list any watercooling support, but it looks like a 360mm rad might fit in the front? It's hard to tell from the pictures, you need space for the ends of the rad as they extend past 360mm.
Fan mount spacing is also another issue for mount rads since the spacing has to be fairly exact.
As for modding, i had to slightly mod the fan mount holes on my case because the rad was 2-3mm to wide to fit, had i gone with an Alphacool rad i would of been fine.