Thanks Leonardo,
This all makes sense except I don't seem to have any junction box on my right lower fender. It appears the B+ wire goes directly from the alternator all the way back to under the dash, I assume to the headlight and ignition switches. I do have the small two terminal block attached to the edge of the oil pan in which one larger terminal ties the heavy wire from the starter to another heavy wire up to the alternator. These are the two new 8AWG wires I had already replaced a while ago when I thought I was only dealing with 35A max system. Now with the AL69X, I am thinking they are insufficient to move 80A, especially when hot. My AWG charts show 8 gauge is only suitable to 65 amps at room temp, and I want to be conservative here. The other, smaller terminal by the oil pan is for the starter solenoid activation wire so no change needed on it.
So, to address your point , I will figure out how to run an additional parallel 8AWG red wire all the way back to the underdash termination points as well as add additional 8AWG wires in parallel from the alternator down to the oil pan terminal and back over to the starter solenoid. From there back to the battery seems fine with the very large cable.
Also, I noticed that the new alternator case has minimal contact area for grounding with the way it mounts, looser than the old original alternator, so I am also considering adding a heavier ground strap from one of the AL69X rear case screws which has enough exposed threads for a terminal lug and routing that to the nearest designated exposed chassis ground, I think there's one under the intake manifold may be good. This should reduce any ground voltage drops to the battery in the highest current scenarios.
appreciate any feedback and thanks for your help! -Mark