Hi,
First of all, sorry for my bad english but i'm italian.
I would realize something like this with raspberry pi and 49 USB block erupter:
But i'm not sure that all is compatible and that'll work when i'll setup the system.
For get the reward, you must be very complete in the reply, (very like detailed explication about critical step in the setup of the rig)
When all the hardware is installed and work i'll send the btc.