I’m not familiar with the pure stock restoration method of grounding on these trucks, but most vehicles from this period had a braided ground strap from the engine to the firewall. Additionally, much of the wiring in these trucks was under size when new, and many of the lights depended on sheet metal parts for a return path to the battery. For example on the 1960 trucks the factory had 14 gauge wire for high beams, 18 gauge for low beams, and 20 gauge for grounds! All of these wires should be 14 gauge. These trucks are also notorious for having random ground problems, particularly in the tail/parking/turn lights. I got so tired of chasing electrical gremlins in my last car I went overkill on my truck.
I went with two basic rules.
1. Everything should have a wired ground back to the battery.
2. Each ground wire should be the same size as the power wire.
This is what I did with mine:
1. The battery is grounded to the engine block with a 1 gauge cable.
2. A 4 gauge battery cable connects the engine block to the frame.
3. From the bolt connecting the battery cable to the frame, another 10 gauge wire runs to a common grounding bolt on the radiator support under the passenger side air deflector. All forward lighting and the electric fan ground to this bolt.
4. A similar wire runs to the rear, and all rear lighting grounds to this wire where it's bolted to the frame rail.
5. Again from the engine block where the battery cable connects, another 10 gauge wire runs into the cab and is bolted to the pedal support. All dash lighting and gauge grounds connect to this bolt.
You don’t have to take it this far, but more is better than less. You can’t have too many grounds. It’s worth the couple of extra dollars in wire and the time it takes to string it, in exchange for never having to deal with random electrical problems again.