Engine Ground wire?

Maybe something to consider. When I was wiring hotrods some years back I would always pick the steering column mount as my primary ground. I never went wrong as long as this point had a good connection to battery negative. Sometimes firewall connections are compromised by rust, welded seams, etc. I also hate to suggest that GM had a good idea, but they always have a ground wire from battery negative to the inner fender. Seems to work for them as GM electrics are pretty reliable.