70 Duster Starting Issue

Did you change the wiring? Get a diagram/ service manual, go over to MyMopar and download one, free

The ignition switch has TWO ignition power terminals "sort of."

IGN1 "run" is hot ONLY in run, comes from the switch, through the bulkhead connector (possibly bad connection) and powers the ignition system, alternator field (70/later) and the voltage regulator. On some cars it feeds smog doo dads, and the electric choke if used

IGN2 the ballast bypass circuit, is brown, comes from the key and through the bulkhead and runs to the coil+ side of the ballast resistor. It is hot ONLY during "cranking" and IS THE ONLY SOURCE of ignition power during cranking