It would depend entirely on the condition of the harness, the bulkhead connector, and the fuse block. Plastic insulation doesn't deteriorate like the old rubber/fabric stuff from the 1940's and 50's did. The mid-80's fuse block will offer plenty of circuit choices for accessories that the 1950 harness didn't offer, and the aftermarket harness won't offer anywhere near the flexibility of a late model factory harness. Use the circuits you need, and nip off the rest- - - -just try to follow the original wiring color codes for things like lights, turn signals, ignition, charging system, etc. If you need to trace a circuit at a later date, or make some sort of an accessory add-on, just use the 84 wiring diagram- - - - -it doesn't care that it's a 1950-era chassis!
The 80's harness will already have fusible links where they're needed, originating at the starter battery terminal, and supplying voltage to the headlights, alternator, ignition switch, fuse block, and other essential circuits.
Jerry
