Thanks for the confirmation, MB Doc. Got some more questions though........
1) I'm unable to see or locate the mark you mention - is it supposed to be inside the distributor or on the outside ? For what it's worth, with the "0" mark on the front pulley / balancer against the pointer on the engine block, the rotor arm points directly at #1 / #6' s terminal post on the distributor cap.
2) I see the ignition advance bob-weights each have mounting points for a spring. My 420 has only one spring on one bob-weight - is this correct or is it missing one of what should be two springs ? If that's the case, guess that could explain the pinking............
Thanks again to all for your inputs............