Well, I wouldn't do it personally.
Would your setup be safe, yes, most definitely.  However the old statement of 1x120 per device is really not going to give you good performance just safe performance, and a little below ambient, but not much.
In general, this is how I spec out for a loop.
1x120 per device is SAFE
2x120 per device will give you solid temps and accommodate some solid clocks while still keeping the temps down substantially below what you would see form air.
3x120 per device, only needed if you are doing brink overclocking, and only trying to keep it stable enough to finish a bench and squeeze the last 25MHz out of a card/proc, largely overkill but can give you some headroom.
 
I usually sit in the 1.5-2 120s per device myself.  1.5 meaning a 360 rad with a CPU and GPU on it, the temp difference is substantial form a single 120 per device. 
 
The 480 you have will keep you from seeing any thermal throttling most likely, but if you start pushing the clocks hard, you may as well be on air.  If I were you I would try to add in a 360 into the loop or even a 240, whatever you have room for and your temps will be miles better.

EVGATech_DaveB
Well, I wouldn't do it personally.
Would your setup be safe, yes, most definitely.  However the old statement of 1x120 per device is really not going to give you good performance just safe performance, and a little below ambient, but not much.
In general, this is how I spec out for a loop.
1x120 per device is SAFE
2x120 per device will give you solid temps and accommodate some solid clocks while still keeping the temps down substantially below what you would see form air.
3x120 per device, only needed if you are doing brink overclocking, and only trying to keep it stable enough to finish a bench and squeeze the last 25MHz out of a card/proc, largely overkill but can give you some headroom.
 
I usually sit in the 1.5-2 120s per device myself.  1.5 meaning a 360 rad with a CPU and GPU on it, the temp difference is substantial form a single 120 per device. 
 
The 480 you have will keep you from seeing any thermal throttling most likely, but if you start pushing the clocks hard, you may as well be on air.  If I were you I would try to add in a 360 into the loop or even a 240, whatever you have room for and your temps will be miles better.

I'm not planning on any oc, I just want it to run until I can afford a bigger case and 2x additional 480 rads and some other things, But until the day I will run 1046 mhz locked as a max on the gpus and 4.6 GHz on the cpu to eliminate potential CPU bottleneck.
So as long as It will stay safe I'm cool with it, and well going to ramp up the fan speed as much as I can when I'm gaming to keep it cool, this is not optimal but it isn't going to be like this for ever so..

MrImSoGood
Do you already have the blocks for them?

Yes and no, one of them is a HC and the other 2 is the ACX cooler once with ek block and backplate ( these two are already installed and i've been running 2x GTX 780 and the 3930k 4.6 Ghz like 4 month now on that 480 and I've had really good temps ) The HC have not been delivered yet, But if I can't cool them all with that 480 for the time being I could just mount one of the ACX coolers on that one for now but... hmm that's not optimal either.