Hey Terryjames,
the air flow rate will strongly depend on how the workpiece sealing system will be on the vacuum table you plan to build. I hoped the Decision help – Vacuum pumps (PDF) table would help you.
I plan to use a vacuum table of similar size as you do, but also smaller elements sometimes, but I am not yet at the stage of final decision. But I think I will buy one of these, but you may also be better off with one of these.
I would always strongly avoid “oilless” or “dry running”, both on vacuum pumps and on compressors, since they often require disassembling and service after less than a year. Also I would avoid making vacuum with compressed air as the efficiency is low.