[deuce_roadster]

I have written this before but if you are running a modern can type coil on a helmet distributor, especially 12 volts you are creating a pretty hot spark from the coil. If you look at the rotor for the helmet type distributors, the place where the carbon runs on it in the middle is directly above the steel shaft that rotates it. I suspect the high tension spark coming from the coil is jumping THROUGH the rotor to the shaft. Many folks put a shrink wrap layer on the shaft to help prevent this. The stock coils didn't produce as much high tension voltage as the modern 12v coils. Sometimes you can get away with it but I know of more then 1 person who has had this problem due to the construction of the rotor wasn't designed for what you are doing and electricity will go to the easiest ground always, and sometimes it is right down through the rotor. Try a different rotor. I hope your press on timing gear hasn't moved, that would be a big problem to fix.
Hope you find the gremlin.