To clarify, you want someone to provide and install new harnesses? Or are you planning on "bringing your eggs to the cook" and hand off harnesses to an installer? You may want to ask around for a local restoration provider, show them catalogs from all the Classic T-bird parts vendors and highlight the harnesses you need replaced, plus have copies of the Electrical Assembly Manual and wiring diagrams for them to use.
If you're providing the harnesses, again - shop around the Classic T-bird parts vendors for new harnesses, and check out places that make harnesses like ClassTech out of Bend, OR (I think they supply many of the 'Bird vendors).
Replacing harnesses isn't rocket science or requires a multitude of specialty tools - it's literally "plug and play" (with a few screws and clips thrown in for good measure) with a good share of contortionism thrown in. Any decent shop with electrical experience should be able to replace harnesses with guidance from the assembly manual, shop manual, etc. if you're really determined to find someone locally to do the work.