Carbs can make funny noises sometimes, especially if it's not running perfectly and the air cleaner is off.
So, for now, ignore the squeak, and ignore the dieseling. Likely the dieseling is because you have something else set up wrong and the primaries are too far open (don't act on that yet)
So if I can butt in to how you chase this, I think you need to start with the black smoke only. Because, that much fuel can cause damage over time
A couple of questions
1 - Does the choke work properly? I noticed he had screwdriver in hand with the choke partially closed. Two problems with that, one, if the choke is working, the idle speed screw shouldn't be, it should be on fast idle and that screw not touching. If it was touching, then the primaries were WAY too far open and we need to chase that
2 - If the backfires were significant, you may have lost a power valve. It's not as bad on modern cars as the old days, but that would cause it to run rich. if it just popped a little, it may not be bad
3 - What color cam on the accelerator pump, and did you adjust it at all? Not saying you should, just asking
4 - Do you know your timing pointer and balancer marks are correct?
So, here is what I would do today if you reattack. Steps 1 and 2 are critical, you can't jump ahead
1 - Focus on the water temp gauge and choke, make sure both work properly. I wouldn't even start the truck until I figured that out
2 - Make sure it's full of water or antifreeze
3 - Once it's hot, idling, , the thermostat opened properly and it was refilled as required and the choke is fully open, idle it as low as you can. Check initial timing again, with the vacuum hose off the distributor, and set it to 12-14 if it isn't still there.
4 - Adjust all 4 idle screws for best idle. Should be within 1/8 either way of 3/4 turns from bottom (Again if choke didn't fully open, not even worth trying)
4 - Reset idle speed if it changed
5 - Check to see if the ported vacuum is alive at idle. (Broken record here, but choke has to be open, because that nipple should be dead at idle, but on fast idle it will stay open and provide vacuum)
6 - If ported vacuum is alive, and choke is fully open, then raise idle on the secondaries and lower the idle screw on the throttle to get back to where you want it. You may have to do it a few times to get it where you want it and have ported vacuum dead at idle.
See how it does on black smoke.
I would not chase anything else right now, doing that will rule out you being too deep in the primaries and a choke problem
I'll be off and on the computer all day if you have questions