wouldn't you have to increase the size of the rad to handle a dual cpu? or I guess it would be like adding a gpu to a normal system.
no custom blocks cad?
make 2 single blocks and braze them together
Bingo. A good system will handle a 2nd CPU just as well as it would another video card. At least 2x120 rad is probably a good idea though, 3x if you're cooling a gaming GPU too.
Since he's not overclocking, you can look at the Intel TDP values for the processors he is using as a guide to how big a rad he needs to run. Even if they are 130 watt TDP procs you are looking at 260 watts of heat dump at 100% usage. I would think a triple should do well for cooling, but since he wants silence I would go with a PA120.3 or RX360 over the others, which have higher FPI.