Such unexplained dying with self-healing a few minutes later usually turns out to be an electrical problem associated with heat or vibration. Places to look are the 38-yr-old ignition switch, the 4-screw plastic connector near the ignition switch, the coil and any other electrical connections involved in getting power to the the ignition from battery to coil- even a loose or corroded stock fuse in OEM fuse boxes. FWIW, a Duraspark distributor runs fine with a stock Ford TFE coil that deletes the problems in using oil-filled coils such as the 'Blaster' you now have. And to eliminate yet another potential problem area, the Duraspark & its above coil runs fine without the MSD box.
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