Well I hope this is the final conclusion to my problem. I decided to replace the plug wires points and condensers. I found the coil ground wire to the top cylinder was broken from its connector but still making contact at least at idle. I imagine under a load or at speed the wire would jump around from vibration and make intermittent contact. I have some more parts on order. Replaced the advance wheel which had a groove, a slight drip at a fuel line and a bracket cracked on disassembly. Hope to have it resolved and water tested before butting her up for the winter.