Sudden death, Engine quit without warning or symptoms Options

[srreality]

On Saturday, during a splendid drive through the Colorado foothills, my newly finished '73 914 1.7 liter quit without any warning. No coughing, no sputtering, no lurching.....just quit at about 60mph. Not a hot day, no warnings. On the roadside I found no loose wires, no melted wires, no outward signs of distress. My fuel pump is located up front, so doubt it was vapor lock. After dragging it home, the next morning I tried to start it........and voila, it started up perfectly and ran like a charm. My local pro looked at it this morning (Monday) and after testing things thoroughly, found nothing amiss. He did say that once in great while, the electronic ignition inside the distributor cap goes bonkers, perhaps from heat and the car would die like that, then start later. Those parts are new (Pertronix),. Anyone else had this experience? Thoughts? Suggestions?

Thanks!