Grumpy Dodge parts department - funny conversation...but still no positive battery cable.

318MoparGuy said
Call M&H fabricators in CA.

They did a cable for my 65 Dart and it was spot on. They also did one for Ulf (@65dartcharger) for his award winning 65 DartCharger! True, not as cheap as making your own but correct and will probably outlast your ownership of the car.