After Market Universal Wiring Harness & Fuse Block?

Somewhat. I rewired the engine compartments in my 1964 Valiant slant and 1965 Dart 273, using a relay/fuse box from a late 1990's Jeep which is long and skinny with 7 relays. I rewired all relays, but had to re-use the wires & terminals since I couldn't source them (fit relay blades, but not Packard 56 terminals). It has ~10 big blade fuses, all powered from a common rail and 6 small blade fuses with isolated terminals (like the relays). I got rid of the factory firewall relays (starter, horn) and ran small ribbon wire from the bulkhead for the wires which just turn on relays now (headlights, ignition, ...). In my 1964, I replaced the bulkhead with one from a 1965 Fury to get the large buss-bar feed-thru's for the thick ALT and BAT wires, which avoids the melting problems of other years (exc. 1963). I am currently doing the same for my 1965 Chrysler, while adding a Holley Commander 950 TBI, and forgot what a chore it is. I have a nice labeler now so at least marking all wires. The cabin wires were still fine in all cars, so I just cleaned up the wiring, fixing messes made by gomers. Search for my post "Modernized wiring ..." for details and photos.