Wiring Help 6.1 w/ factory harness

I am running a 6.1 in my 70 e body with manual tranny
So here's what I'm doing .

1st: running 6.1 with manual tranny
2nd .using factory harness thruout
3rd: purchase thunder classic dash with auto meter gauges

I know that I have to put the wire from the alternator to the starter and upgrade it to a heavier wire . But the original wire that ran to the back of the volt meter ? where should it go now?
and the black one that goes from the starter relay to the back of the amp meter?


I have most of the dash together but want to know what is next with these wires and how to use the originals
any pics? diagrams?
Thanks for any help
John.