If they were leaking at the hex, there will be a carbon ring at the base. Most of what you see is crap from rotten wires. The black shadow may be some leakage from the boot being brittle and not sealing anymore. That is quite common.
The center electrode looks to have a crisp edge, with no rounded appearance from wear.

Really cool car, Tim. My '67 Z28 that I bought from the original owner has the same 1114344 part number on the starter solenoid.

The cluster is pulled for cleaning, the clock is pulled for rebuilding and cleaning, and then there is more cleaning.
https://i.imgur.com/HDmm1sIh.jpg

https://i.imgur.com/JuqT2Bvh.jpg


Squeaky clean windshield frame for sure!
https://i.imgur.com/DJOISfdh.jpg

https://i.imgur.com/c5XxlPGh.jpg

https://i.imgur.com/L0g5b9Jh.jpg

https://i.imgur.com/yNf8jNch.jpg

More cleaning......
https://i.imgur.com/WyQ6Oi7h.jpg

https://i.imgur.com/eY1Ur8qh.jpg

https://i.imgur.com/gO2bQuHh.jpg

You're killin' us with these pics. That car will be sold before you're done cleaning...:headbang:

If I was in the market, you'd already have a down payment...:worship:

----I wish I had kept track of how many times I have done exactly the same dash cleanup as you are. Anymore it's becoming an unwanted chore as arthritis keeps me from twisting around in the passenger compartment on my back. Looks to be an outstanding original 65. Keep up the good work. Wish I could have met you at MCACN, but couldn't seem to get away from my swap space anywhere near as much as I would have liked.....Bill S

The older wiser me pulls the seat out, take off my shoes.........make myself comfortable.......and chip away at it. I suppose it's kind of sadistic, but I feel the end product is always worth it.

CAn you share a picture……LOL!

I'm starting to like that car, Tim.

I already acquired one mid year Corvette from Wisconsin in the past 10 days, so I'll hold off on this one.

----All of the above, but it still takes a toll. Wonder if I'll ever grow up and straighten out....Bill S