Dramatic Backstory:
I bought my first C10 in April 2017, an '02 with 48k on the clock. Loved it. Long story short(end), it's been to the back trails of West Virginia (yes, I offroaded my Connie, shame on me), Canada, Kentucky, and North Carolina, sometimes with sometimes without a trailer, and after 20k miles, my baby has failed me. The main fairing stay broke, the bevel drive leaks and the clutch slips at highway speeds. So at a meer 67k, I stripped the fairing and made her a naked sport-tour. Love it. Pulls on 1000's, looks like a crappy old cruiser. Bought myself a new (yes, zero miles, new) KLR and upfitted it for long haul tripping, but I miss my Connie. With the fairing stay gone and no simple solution in sight, I bought a 1991 C10 with unknown miles (title says 65k, odo says 48k, so who knows for sure). Not running, in several boxes.
The Plan
Once the bike is operational, I'll have a welder reinforce the fairing stay where it broke on the 02. I'll install all previous accessories from the 02 to the 91 (crash bars, trailer hitch, etc.). I'll also move the front forks from the 02 to the 91, so I can have the superior brakes and wider front wheel. I'm going to move all of the 02 plastics to the 91. Essentially, it'll be a 91 in an 02's clothing. '

*edit* Attached pic from the day I brought her home.

 
It goes without saying but, I'll say it. Plenty of pictures, please.

Got the bike running tonight. Carbs and airbox are reinstalled. Bike runs, but has a severe run-away idle. My local bike experts (read "friends") tell me it's probably the carbs out of sync, so this weekend I'll trailer the bike to my buddies garage and we'll go ahead and sync them up.
In the meantime, I'm going to go ahead and change the god-knows-how-old fluids in the bike

Google Drive of pics and vids https://drive.google.com/drive/folders/1HccaX4Bext5KIBLtJ9Jf455VCkRM3f3W?usp=sharing
Link has folders for each update as I post them.

Edited

First two videos, good idle. Last two, run away idle. Thoughts?
https://youtu.be/_3OUdQ2RA3o
https://youtu.be/mW9iFWJNHuY
https://youtu.be/Xumfpa8540A
https://youtu.be/EPPHa8lADi8

Did the carb sync today, bikes running much smoother. Surprisingly only carb #2 was out of sync.

Check the carb boot on #2.
Possible you have an air leak.

Ride safe, Ted

Sorry, I didn't get to put much in there as I was posting off of my phone.
Good news is the bike idles more smoothly than it did, but still very rough. I'm changing the fluids this weekend so hopefully that will help. The bike is smoking very badly from the bottom of the right engine cover when the bike is running. I'm hoping this is build up from sitting 5 years but I'm sure it's something more ominous.

I don't have my C-10 here to check exact location.
But, smoke under the right engine cover could be the seal on the balancer shaft leaking.
If so, EZ to change.

Ride safe, Ted