You could move the dimmer to the column too but you don't have to. It's three wires. Power from headlamp switch, Low Beam and, High Beam.
The turn, brake, hazard, horn and, "ignition key inserted switch" harmonica plug may need to be adapted to mate with the 81 cab harness harmonica plug #12004147.
The 85 & 81 wiring diagrams show the same pinout and the same 12004147 plug so it may just plug in.