[Osage Orange]

You said it ran for a short while as smooth as silk? It isn't timing gear misalignment. That won't ever run smooth one moment, not so the next. Simplest next step is starting fluid. If it won't start with that, stop looking at fuel and pour all your attention on the spark and electrical. Change the condenser first. I'm betting it is that, but know from experience that the wire from the switch to the distributor is notorious for shorting out, so that's my second bet, doubling down to get my money back.