Allis B grounding location

Being an electrical guy for the past 50 years, I never thought anchoring a Battery ground to a pipe was a good idea. To me, a nice flat area would make a better ground. Although it worked for years where they grounded it. The Torque tube would be a pretty good place to ground it, or to a nice clean spot on the Bellhousing area. Its always good to make sure the grounding rings and where the Starter motor mounts, that the grounds are clean & solid. The 6VPG system relies on its grounds to function properly. 1/0 cables are a bit overkill, but in that department, bigger couldn't hurt.  One gauge cable would be the norm for 6V systems. Running the cable to the Starter motor is always a good idea to insure a ground providing the Battery was far away. In this case, the Battery is right next door to the Starter, so it wouldn't be needed. On Streetrods and Race cars that I've wired over the years, when the Battery is located at the rear of the vehicle, such as in the trunk or frame rail mounted, running a ground to the frame rail as well as running a ground cable parrallel with the hot cable up to the Starter utilizing one of the Starter bolts to anchor your ground to, insures a good ground to the Starter motor. I usually install a aux. ground from that anchor bolt to the frame rail right where the Starter is to make a grounding loop. The problem with the early AC Tractors is the Starter motors are not bolted to the engine or bellhousing limiting a place to put a good Starter ground.  The pinch bolt is all you have, and I wouldn't use the pinch bolt for a grounding anchor.  HTH

Steve@B&B