You should have a hot wire from the + terminal of your starter switch to the + terminal of your ammeter. Then a wire from the - side of the ammeter to the B (battery) terminal of your ignition switch. The wire to the lighting circuit will be tied into the latter wire somewhere.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.