Actually not. Rick only bypasses the bulkhead connector for battery charging. All other power needs go through the original connector.
I wouldn't give any advice about modfications to a '75 without seeing the layout. It may already have wiring that splits feeds, somewhat like a '76 does.
If its a flat connector, that may work. Sometimes the Packard 56 terminals and connectors will work and sometimes they are too tight or too loose when mated with Chrysler terminals, which are closest to Packard 58.
Dave if you can post a screenshot and/or photo of the link location on the car and/or the diagram, that would be helpful.
Every year is a little different and '75 is right about when additional feed wires and fusible links were being added. A lot of the later fusible links use a bullet type connector which has more contact area than the flat terminals.
