Amen, Jerry
It might not be "original", but it sure is logical.
That 00 gauge ground cable (I believe in in overkill) from the 6v battery to the 6v starter bolt might be expensive, but, it makes sense and makes for a fast spinning starter.
And, I have 00 ground straps frome frame to clutch-housing on both sides, and from clutch housing to firewall (inner-fender rod-to-firewall bolt on passenger side). I think these were specified for the RPO/Accessory 6v radio?
(00 gauge might not have been specified, 2 gauge was probably "standard", but what the hey?)
Clean-to-shiny and use conductive-grease on all connections. They will not corrode/oxidize in your life-time?