NOS wiring harness worth it?

I found a NOS wiring harness for my 42 year old bike... would that be a worthwhile purchase? The bike was running (albeit not well) before I started 'improving' it. I don't mind spending some money to improve reliability but I have no idea whether this is likely to help...
Thanks!

depends on how much but i would say hell yeah, ill be looking into that also vs wiring it up myself because you can look back at a stock wiring chart and know exactly where the wires go, for example the coloring of the wires.

Theres a real good chance that 42 year old wiring harness is junk. At least partially. Unless it was stored in a climate controlled room or wrapped in airtight plastic, the elements will not have been kind.