The ground from the rear-mounted battery runs to the chassis about 2 ft from the terminal through a 2/0 Gauge ground wire.
The block has two grounds, it seems to me, though one is not technically connected to the block itself. One actually runs from the timing chain cover to the chassis on the driver's side and measures ~0.380" sleeved, which I think is 4 Ga, as that's the diameter of the sleeved alternator power wire that is stamped 4 Ga. The other block ground runs from the block itself to the chassis on the passenger side and measured ~0.370", again I think that's 4 Ga.
There is no ground running behind the intake on the driver's side that I could see. I do not yet know where the a/c system ground is, but that's for another time. Does it just ground to the block, too?
The figures you've mentioned are obviously stock numbers. The ones I posted were based on researching my specific components, but I didn't take into account running the rear defrost, wipers, radio, and I was guessing at the blower motor. I'll include them in my data. Looks like my base idle during daylight should be in the 85 amp range (w/o radio/lights/blower/wipers/defrost). My my... even the 3G 130 amp alternator is only supposed to put out 80 amps at idle. No wonder the stock alternator was terrible.
I have attached a picture of the power wires on the alternator. Is the left-most wire in the pic one of the black/orange wires you're talking about? There are two of them there. So, I assume that's what you're referring to. Apparently my installer didn't know about what you're referring to. What does it do? Will disconnecting it have any negative side-effects that I'll need to remedy? Should it be replaced or just disconnected? One seems to run to the starter solenoid. I lost the other into a cable bundle on the driver's fender. Maybe I'll just add in-line fuses to protect those wires.