The measurements really help. I doubt you need another harness, unless the insulation on your wires is old and brittle. The copper should be fine. You just need to clean the connectors, and maybe solder the crimps. You can remove the terminals from the bulkhead connector fairly easily by squeezing the long way w/ needle-nose pliers. Look at photos of "56 terminals" on ebay to understand. Label the connector w/ a Sharpie A-H and record the color wires before removing, or do 1 at a time. Spray Contact Cleaner in female terminals or ones you can't remove.