I'd be real hesitant to accept what works on some other brand of engine as gospel for all engines.

GM may very well have used ported vacuum for whatever reason that is completely inapplicable to MoPar engines. During the emissions time frame that GM engineer speaks of Chrysler used lean burn whereas GM used air injection and cats well before Chrysler had to. So something in the engine design was very different between the two.

I can also tell you this, my 65 Cuda uses ported vacuum as did my 64 300, both well before tail pipe sniffing became the norm.