Put the mosfets, vrm and ram in series with the cpu loop, as they are closer, and less heat is emitted by each component (GPUs emit stupid levels of heat *cough*R9 290X*cough*).
Be aware that this setup will be hugely complex, so plan carefully and make sure your case will fit those radiators.
Dont cool the southbridge though, that only controls more legacy based connections, and connecting that up is a bit of a waste, as detrimental to the GPU, since due to positioning, the SB and GPU would have to share a loop.
I've only worked with dual 240mm rads with cpu, cpu, mosfet and vrm cooling before, so I cant give any ideas on how WCing the RAM and NB will affect overclocking performance and thermals.
Good luck!