Bulkhead wiring/fusible link questions

I have a 73 Duster and, hopefully, within the next month will be bypassing the bulkhead connector. I have the 73 manual with the wiring diagrams and this diagram shows a 60A alternator option that bypasses the bulkhead so I am planning on copying this for the most part. This leads me to a few questions...

1. Fusible link size: I am planning on using 8 gauge wire as shown on the wiring diagram. The places I have looked say to use a fusible link 2 sizes smaller than the wire size used which puts me at a 12 gauge fusible link. The wiring diagram shows Plymouth used a 16 gauge fusible link for both the 60 amp alternator and normal alternator wiring, so I'm not sure if I should use a 12, 14 or 16. 14 and 16 are readily available at the local parts stores, but I think I'll have to order a 12.

2. Fusible link connection method: I was thinking it would be nice to have an easily removable connector so I've thought about splicing in a bullet or similar connector in case I have to replace the fusible link down the road. On the other hand, neither version of the car (original slant six or current 340) have ever melted the fusible link (the car has been in the family since 73) so should I even worry about trying to get a removable connector or just splice it directly to the wire?

3. Bulkhead wiring: The wiring diagram indicates that the bypass wires from the alternator and the battery are connected (with fusible link at the starter relay) directly to the ammeter and the "stock" wires removed (or at least I think that's what it is telling me) from the bulkhead. This seems simple enough and the main power splice on the alternator side inside the car would be fed from the connection at the ammeter. What I'm not sure about is that my bulkhead points P and Q are connected at the motor harness and the diagram doesn't say anything about changing that wiring. P is the 12 gauge black wire alternator wire (and the most corroded looking connection) and Q is the 14 gauge brown wire that connects to the ignition coil and the ballast resistor in the engine bay and (converts to 12 gauge) the start position on the ignition switch inside the car. What does this parallel connection do? Is there a way to bypass it or is it just easier to fix the connector in the bulkhead and leave the stock alternator wiring alone?

I've been putting this bypass off for a while and hope to get it done in the near future. I have less than 11V in the car when anything is turned on (run position, headlights, whatever)

Thanks!