Is this an odd '67 Dart Voltage regulator?

IMHO most likely not an issue BUT....

If the field wires on a Ford alt draw less current than an mopar, then maybe it is hard on the VR, if it was me I would put it back to OEM and use the year appropriate VR, modern replacements will be electronic regardless of the style.

Don't forget to match the VR to the alt if the alt is not year correct.