Bulkhead bypass vs ammeter bypass

I’m rewiring the whole car because everything was trashed :)
The bulkhead connectors crumbled in my hands as I removed them and the wires were cracked and bare in some places.

I want the stock stuff to work, just want to protect the new harness however I can. Oh and I already have the higher current alt.
I rebuilt almost every harness in my car except the main dash harness but mine was in good shape. I did check every wire in it.

When I rebuilt a harness, I sized up the wire 1 gage. The manual tells you which wires are which gage.