I don't know if the Copal #1 has that switch -- perhaps the much older ones might? The newer ones do not have it as they were made way after the use of flash bulbs ended.
For just general info (I know you know, Brian), the M setting delays the opening of the shutter to allow a flash bulb to build up to full power -- but with electronic strobes the shutter would open after the strobe has fired and died out. The X setting opens the shutter and fires the flash at the same time.
But another way to test would be (if the ambiant light is not too bright compared to the strobes) is to open the shutter on B or T, then manually fire the strobes, then close the lens.