Overcharging problems

That's both more true and less true on a '75.
More true because there are more connections and junctions.
Less true because that crazy diagram is even less representative of the routing for that year.
J1 feeds the ignition switch from the alternator output line R6. It's a longer path from the battery but a shorter one from the alternator. Just as important the current from the alternator is split before the bulkhead multiconnector.
That's all good. But it calls for a second fusible link, so that limits the loads fed by J1.
Also AFAIK '75 still has the 'engine connector' introduced a couple years earlier.
1975 schematic and photos