I think a Dual DDC is the best choice for your loop. Else do this way -
Res > DDC Pump > GPU Block > Rad > Swiftech Apogee with DDC Pump > Rad
This is the best choice and I am sure you will have high flow rates. If none's possible , get a D5.
P.S - Add the 240mm RAD before the 120mm one as it will increase flow rates.
Your welcome , water cooling can get addictive as you get more familiar with it and see all the different parts that there are and what you can cool with water. You can end up with several loops and multiple pumps, reservoirs and radiators.