Stupid Ground Question

mopowers said
1. Is a ground strap/wire necessary from the engine to the firewall if one exists from to the radiator core support?

I say yes, others may disagree.

mopowers said
2. If so, what size wire/strap is adequate for this?

My 74 has a braided strap from passenger head to firewall, along with battery to head and battery to core support.

The braided strap is like this, I would guess you might find one locally at NAPA.

Dorman Products 60213: Ground Strap Universal | JEGS