Since the engine came from the aviation world, have you checked with aviation engine rebuilders to see if they have suggestions?
Otherwise try some of the specialist carb shops. The carb is unique enough (compared to cars, how many people restore tanks?) that they are unlikely to list it, you'll probably have to call or e-mail
http://www.thecarburetorshop.com/PartsStromberg.htm http://www.thecarburetorshop.com/Contactinfo.htm
http://www.carburettorspecialists.com/products.htm
http://www.jalopyjournal.com/forum/s...d.php?t=540762
I haven't dealt with either vendor above but The Carburetor Shop has a good rep on stovebolt.com forum (and contributed to the jalopyjournal thread given)