Well, I've just put an order in for a PA120.3, which should be enought, even if I decide to watercool my 4850 as well.
The rest of the kit should be ok, I got a DTek Fuzion V2 when I replaced the mobo/cpu and I'm running an Ehiem 1250 pump (which will be the only watercooling piece left from my original loop)
My only issue now is that a 120.3 rad doesn't actually fit in my case (Yeong Yang Cube) and as such I'm going to have to make some holes...