I overdo everything with my 6v truck battery cables and grounding straps.

00 gauge cables from/to battery:
- positive to starter-button post
- negative to a starter mounting-post (for ground)

Three 2-gauge or heavier ground straps
- clutch housing to frame on driver side
- clutch housing to frame on passenger side
- coil mounting screw to fender support-rod bolt on the firewall

All attachment points shiny until copper-impregnated conducting anti-oxidant goop is applied before installing attachment bolts.