Thanks in advance.
That should work fine two per break out board with 8 pci 6 pin plugs on the breakout boards ... what's the PSU ? ... use small fans some thing like this https://www.amazon.com/gp/product/B00G05A2MU/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1
those fans are awesome, i have a few after I discovered them.
Blowing on the break out boards or the plugs might over heat and burn out ( and that can be real bad ).....So Watch those plugs at first to make sure they only get Luke warm to the touch any warmer might be bad over time and you might burn down everything .... if you use two miners per 2400 watt server PSU, which i hope you are, run that on a 220/240v 30/40 amp line not a 110/120v 15/20 amp line bad idea puling that much power off a 110/120 line .
You can daisy chain up to 6 devices PER AUC, it's kind of unlimited PER RPI, the AUC is the real controller inside the the miner that runs it all ...so that's 6 per Avalon 6 .. if that makes sense ...
AUC: Each AUC can connect up to 6 devices.
https://en.bitcoin.it/wiki/Avalon6
I still have one A6, I use from time to time ( I'm a hobby miner an use GPUs and Script miners, too) ..and thinking of buying one of the A741 aka A7, I'll keep calling it till they actually change to the name to some thing other then Avalon 741 aka A7 etc ...