console harness should come forward toward dash and plug into the dash harness. There should be a console feed, but not in all harnesses. As suggested use a schematic it should be marked I believe the wire is orange same that illuminates the radio.
His 69 will have the reverse lamp switch at the shifter so his console harness will have those 2 wires. A 71 under dash harness has nowhere to plug those in . Those 2 wires are routed through the bulkhead connector from 1970 up.
If he uses a later model trans and 3 post neutral safety switch he can use the 70 up trans harness and forget 2 of the wires in his console harness.
His console harness would then need only the orange wire for the shift indicator lamp and optional pink wire for a lighter well in the console.
So that's one of the differences addressed. Only umpteen more to go :)