looks good.....I'm picturing the cycle like this.
Pump>Radiator>CPU cooler>Resivor>Radiator>GPU cooler>back to pump
The Siftech kit uses a bracket to mount the rad outside the case.......if you got the kit with a dual rad it can still fit outside the case using the bracket.
The rad you linked to is a dual 80mm Rad!!!
You can add another Rad to the loop, but you need to be sure it will fit. for that rad to work you want a space in your case to support 2x standard 80mm fans!
What case are you using? Or can you post a pic?
I can't recommend any vendors as I'm in Ireland ;)
I'm sure others can help!
try
http://legitreviews.shopping.com/xPC-Sw ... _Kit_REV_3