Well the car will not be street driven or qualify to be tagged right? That means all of the wiring comes out that doesn't make the car run right? So the only wiring left will be gauge harness and ign. harness?
If I remember right you were going to do an alum. plate for the gauges (autometer or whatever but not stock or in the stock bezel). So you can run generic wires to the gauges you install in a panel later and you won't need wiring for headlights, washers, wipers, TS switches, door lights, interior lights, HVAC wiring/cables, etc. I would tear it all out (wiper motor, etc.) and spray bomb it. You can always fit a dash panel, cut some wiring, etc. until you take it to paint, less in the way and if you prefit you can quickly install when you get it back from paint.
Will you still need to keep brake lights? fuel gauge? just trying to think of wiring that goes to the rear of the car.
Jon