My version is linked early in this thread. Where I have the MSD power, you can connect your new harness
With my '67 I choose to run a second alternator output wire in parallel instead of replacing the original R6.
Since I already had a headlight relay harness connected at the alternator, I kept that too. If it wasn't already done thatway, I would have connected at new distribution point (single terminal stud).
Here's the diagram for the '73 B-bodies with 60 amp Fleet alternator & battery.
Some more versions here
Another heavy duty approach was used on A-bodies with rear window defrost.
On those, the battery and the alternator wires were fed through a grommet in the firewall. The ammeter's R6A stud was the distribution point.
Four examples linked here