The ground point for the alternator is just the mounting bolts, I added a wire from a bolt on the alternator housing to the negative battery cable at the chassis.

Check shift rod bushings, incorrect shift rod length from worn/missing bushings can cause the NSS to be mis-adjusted, resulting in a starter lockout and lack of reverse lights.

The reverse relay is in the NSS, could be the contacts have fused.
Lastly, the electrical portion of the ignition switch maybe at fault.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022