Some pictures in my post on the IFSJA board for harness repairs - mostly Packard 56 connectors like our A bodies.
International Full Size Jeep Association - View Single Post - Cold Temp/humidity sensitive Ignition
The Packard 56 are decent design with wide flat spring loaded contact area on the female terminals.
Sure there's better sealing ones today if you want to go that route, but these aren't bad.
My suggestions for a good job whether its selective repair or 100% new wires and terminals:
Tools:
Good set of crimpers for "open barrel" terminals from 18 to at least 12, preferably 10 or 8 gage.
The larger ones can come into use when joining two wires at a terminal. Astro sells a nice compound action crimper but the jaws are two wide for the male terminals. :( American Autowire sells a slightly a set of proper crimpers, slightly less expensive than the real thing.
Terminal removal tool.
Seems silly when a cotter pin or small screw driver will do, but they do save time and minimize damage. I think they are worth it. Best in use is the single prong version. Multi-prongs sometimes interfere with the adjacent terminal cavities.
Wire stripper
Screw driver. May still need to use this for removing the male terminals.
Materials
Wire: My preference is from a marine supply center. Slight more copper, Tinned surface, insulation suitable for engine compartments. They also have a ton of colors and can cut what is needed. Second preference for engine compartment is with insulation for that environment (heat and oil) such as GXL or (IIRC) THWN rated insulation. Otherwise GPT (general purpose primary) is fine.
Terminals and Connectors: I've bought Packard 56 from Waytek Wire amongst others. There does seem to be slight differences such as whether they are tinned. The male terminals also seem to vary in dimensions?? I didn't notice that until working on the Jeep - but I;d try to find some that are same length as origin l and have the little tabs. (see pic in my first link for comparison of what I found on the Jeep). If the original connector (housing) are OK I reuse them.
Design:
There's no way in hell I would run the original a-body wire sizes to the headlights. If you're not going to a headlight relay system, increase all of the headlight wires to the next larger size.
Connector ID Guide:
Automotive Electrical Connectors
