If the wire is good and the covering is pliable there is no reason not to reuse what you have.
If your running old loads off of new relays then run new wire on the load side and use old wire to control the relays.
Thanks, I have a whole new wiring diagram mapped out and I'm wiring a fuse & relay box as we speak. I was going to use the wires for the front parking lights and horns from the spare harness as well as the drivers headlight socket and create a complete forward harness prior to install.
I figured since the harness was serviceable I'd check the market and since there are new replacements that can be had I guess I'll go with plan A.