I don't know what 'this case' is to see if it fits.
A 240 is NOT enough to cool to 570's. A single 570 at load produces around 243watts of heat. Your average slim 360 rad can dissipate around 525watts with 1800rpm fans; a 240, obviously is 66% of that size meaning = 346watts.
If you are adding your CPU in the loop, consider adding another 140mm or a 2x120 (240) rad.
I guess I am not following...are you saying a stacked radiator 'sandwich'? No, you don't want to do that...very poor performance degradation on the 2nd in the airflow chain (as much as 40% lower performance).
I'm saying you could use a 2x120 (or 2x140) rad with a 200mm rad and be fine.
i was looking to take out the front hd cage and mount a 240mm there as im guessing that is all that will fit. A 200mm would be too large wouldn't it and you say that a single 240mm rad would not cool 2gtx 570s so my only option would be to sandwich them or stack them unless you have a better idea.
No, a single 240 isn't going to cut it. I also don't think you are going to get them in there, sandwiched, either.
There appears to have been a trend lately where folks have bought cases and want to shoehorn a complete water loop inside, only and there's barely enough room inside to let light in with the case open.
You're going to have to get creative on this one...mounting on the back or sides is your only other option, or build a pedestal for the rads and pump, etc.
As in a single GPU? Yes, a single one. No CPU, though...you're talking a single-GPU-only loop? Why not just get good aftermarket air coolers for the GPUs and CPU and make sure you have good case airflow? You could do that for less cost and get pretty decent temps. I just don't see how you are going to squeeze what you want into that case without some serious modding...inside and out.
Making a pedestal is pretty easy...simply a box you put stuff in, and sit the case on...or even could be a remote box with tubing between. This would keep the radiator fans further away (guessing this is a HTPC build?)