My search attempts come up with very little.
What would I expect to pay to have a complete harness replacement by a shop ?
Labor only ?

 

40-60 hours @ $100/hr if the interior is still in the car.

 

The first question is, is this an exact replacement harness or a "painful" generic harness that will require a lot of custom fitting and routing?

 

That remains to be decided.
I guess it depends on availability and cost.
Do you have a source for a 100% replica replacement harness?
The wiring is a mess, tou can strip back any wire and get green dust from end to end.
Sometimes things work sometimes they dont.
The local guys are tired of piecing it together, lol.
Dont blame them.

 

To do this correctly (whether exact replacement or upgraded/generic) will require the removal of the dash, seats and console if you have one. I just installed an American Autowire kit called the "Classic Update" that has all the factory circuits plus additional circuits for modern accessories and it uses the modern blade style fuses. The documentation is excellent, and very easy to follow. I've added power windows, seats and door locks, an 800-watt stereo system, cruise control and a keyless entry alarm system. The AAW kit had all the circuits I needed.

Rodney

 

If they have the skill to install an aftermarket wiring harness they should have the skill to make the necessary repairs to an OE harness.

 

Assuming there is enough of the factory harness to even bother with repairs. The OP says there is green dust coming out of every wire, that suggest corrosion inside the insulation. I would find it difficult to believe a harness that badly corroded wouldn’t have an equally corroded fuse box. Combine that with 50 years of “customized” additions and half assed repairs, where do you draw the line?

Im very comfortable with automotive electrical work, but time is money. Why spend a bunch of time and money fixing headaches?

 

You can find good, used harnesses for plug and play. The AAW update kit is really nice, though. Glad I was priced reasonably on the one I did.

 

I've done this to my ragtop - new OEM repro harnesses front to back - not really a hard job if you're working on a complete car that hasn't been butchered with a host of hacked alterations, the dash harness is the most complicated of them all in terms of routing and number of connections but actually fairly simple if you're methodic in your approach - it took me about 15-20 hours over a few days to do my car throughout, in stages so I wouldn't get impatient if I hit any snags. Most of that was the dash harness due to its routing and connection complexities but all essentially straightforward.

I think the trunk-mounted rear lights harness is actually most difficult even though it's easy to access, because it requires you to lower the fuel tank to connect the sender wire. So if you're doing that one, save it for a day your tank is almost empty....

An OEM dash accessory harness as well (for the under-dash door, map light and lights over dash switches), is also an easy drop-in replacement at that point in connection with the main dash harness.

for the dash, I took some photos of the disassembly process as I worked and labeled my connections on the new harness as I pulled the old ones apart in the dash, so once I laid the new one in, had the dash fully back together within an hour. In my case, I also replaced my original AM radio with a Custom Autosound stereo in the dash at that time, so its small chassis body leaves a huge amount of room behind the dash to work with.

you will need to remove seats (also console if you have floor shift) and carpet to run the intermediate harness across the floor from front to back but that's probably the worst of it. Dash harness can be accessed by dropping the steering column down (doesn't require removal) removing the guage cluster, radio, lower a/c vent panel (if an a/c car) and if you're really ambitious, the glove box liner (which is good idea to replace anyway if still original to the car.

beware - you won't escape the MAW (might-as-well) temptations during this process - with certain things apart, it's tempting to do other things that are now opportune - such as great time to replace carpets while you're at it if they're worn out - also a fairly simple effort if you use a good replacement (ACC was my choice). AND you can lay down sound deadener on the floor at that point if you wanted. You could upgrade your radio to something new/smaller (again - HUGE space savings behind the dash from these new drop-in stereos), replace all your gauge bulbs at that point, maybe upgrade to LED... stuff like that.

American Autowire and M&H Electric I believe are the two main manufacturers of OEM replacement harnesses and each are sold at a number of vendors such as Year One, Fusicks, OPGI, etc as well as thru EBAY (and the manufacturers themselves have their own websites to buy them from).