Hardware for 50 PSTN lines and 150 extensions with Asterisk

I need to connect 50 PSTN lines and handle all incoming calls with asterisk and also at the same time handle outgoing call from 150 extension.
I am thinking about using the sun fire x4100 server and install on it the asterisk PBX, also using two Digium Wildcard TE411P to interface with the lines and extension, but I need the hardware to interconnect those 50 PSTN lines and those 150 extension with asterisk.
what hardware to use in the side of PSTN and POTS?, what channel bank?, what configuration?

thank you for helping me