You can swap injector wires without issue.
Be careful with solder. It will wick through the wires, which seems like a good thing, but it isn't because the heat will make the insulation flimsy and it becomes an easy spot for wire breaks (right next to the solder joint.) A piece of tight fitting heat shrink helps support the wire next to the joint.
Regarding the switch on the shift shaft, the factory used that for reverse lights and neutral safety, as you're aware. But you can use the column switches, if using a column shift, and everything works properly OTHER THAN calibrating the column shifter to the shift shaft. The concern, as might already know, is starting the car when the transmission isn't in the correct gear - it can cause for some excitement and/or mayhem.
Be careful with solder. It will wick through the wires, which seems like a good thing, but it isn't because the heat will make the insulation flimsy and it becomes an easy spot for wire breaks (right next to the solder joint.) A piece of tight fitting heat shrink helps support the wire next to the joint.
Regarding the switch on the shift shaft, the factory used that for reverse lights and neutral safety, as you're aware. But you can use the column switches, if using a column shift, and everything works properly OTHER THAN calibrating the column shifter to the shift shaft. The concern, as might already know, is starting the car when the transmission isn't in the correct gear - it can cause for some excitement and/or mayhem.