Drag Car Wiring Advice

Im building a 1972 Dodge Dart, 10.5 second goal. The car has been stripped to 2,800 pounds w/the cage installed. I have no dash panel anymore, guages are separate, and steering column has no ignition key unit anymore. I want to have lights, inside and out. Otherwise, I just need wiring to run the car down the track. I'm not planning to have any fancy computers or monitoring units.

I have the OEM Wiring Harness, but nothing is marked.

Question; Do I install the original wiring harness and figure out where to run the wires where they need to go (just not connecting wires that go nowhere), or should I buy an aftermarket Wiring Harness, and rewire the entire car? It doesn't seem like that would be too difficult, and certainly a little cleaner.

I appreciate any advice. What have you done? Thank you,