Wiring Harness ?

[Job]

Can a wiring harness for a car with cowl lights be used in a car without cowl lights and two bulb headlights? If so what changes need to be made? I have a wiring harness I purchased a few years ago, can't remember if it was NOS or NORS but it is old and appears to be for cowl lights as there is an extra wire in the harness as well as a separate harness that matches catalog pictures for harnesses with cowl lights.
Thanks for your help, Job