Battery ground wire and hot wire section

I use the chassis as a ground path all the time. Weld a nut on frame and attach cables. If the car is frame connected with welded structures, even better.

I run 00 cable for both the starter cable and all grounds from battery/frame/engine. Don't skimp on grounds as energy will find other paths for grounds. If you ever see a speedo cable that is melted, that's usually from a bad ground path for the starter.

You can pull auxilliary grounds to everything else off those big ground cables.

EFI and other sensitive electronics need clean grounds if being used.