Probably the reason the MP pinged at slightly less total is because the MP probably advanced quicker (weaker springs) than the Mopar.

In theory, distros are pretty simple. If you imagine there is NO mechanical OR vacuum, the base timing is what you set.

The mechanical varies with engine speed, the strenth of the springs, to set the RATE of advance, and the slots that limit the travel sets how FAR (degrees) the advance.

Same deal with vacuum. Some are adjustable. How far they move is the amount (degrees) and whatever internal springs--and whatever vacuum is available at the carb--determines how "fast."

So if you put in lighter springs, and the advance comes in "too much too soon" you might ping at less total.

One suggestion I ALWAYS make is to degree the damper using a "positive stop" so you KNOW where the marks are. This also avoids the need for a delay timing light---I've seen a few that were not accurate, or became inaccurate after being banged around somewhat.