Stuart,
Okay, you're probably right --- I was overthinking it and just assuming that juice wasn't getting through to the plugs. I should just reinstall the carb now and run a gas line to it, and see if it starts. The 12 volt battery cranks the engine real nice, but the new 6 volt I bought is very lame. It might be discharged. The wiring diagram I used is part of the online Chevy manual:
http://chevy.tocmp.com/1948_51truckshop/51ctsm1202.htm