High Amp Alternator Charging System Question

No.
The wire sizes need to be based on the loads.
The battery does not load, or should not load, an alternator to a point where a 2 gage wire is needed. If it does there will be bigger problems.

There's some good posts discussing and showing some safe trunk battery wiring strategies.*
With EFI, power for the pumps etc will need to come from the battery during start up and then from the alternator during run.
This puts a greater demand on the alternator and alternator output wire during run. Size for that load.

*
Here's the threads with diagrams and photos for a couple of safe battery in trunk arrangements.

https://www.forabodiesonly.com/mopar/threads/battery-relocated-in-trunk.439736/
questions about battery disconnect wiring

Trunk Mount Battery - Wire Routing

Adding electric loads, especially equipment that will be running during start and while idling can cause problems with the original wiring strategy.
The original system only drew on the battery for starting and to keep things running for brief periods such as when at a stop light with wipers, heater, and lights on.
This post suggests two approaches when adding electric fuel pumps and fans.