Henry,

I'm assuming you already have cannon foundry info from Hazlett, etc.? A few months ago from the text/tables I made myself a crude list of field arty produced by the foundries there before surrender of New Orleans and I came up with ~81 pieces known or most likely produced--enough to equip from 13 to 20 batteries depending on whether they were four or six piece batteries. That's a very substantial contribution considering the limited time frame. (Nashville with ~56 and and Memphis with ~68 had similar productivity as well.)

On topic:
Gorgas certainly seems to have done a good job marshaling his limited resources.