I thought that might be the case with your engine speed, but I couldn't pass up such a golden opportunity to bust your balls about it.
thanks for the pics. They really do help. The carb is a Holley model 2300 (2bbl) with side hung float. Could well be original. Its the correct design for the model year of the truck. In the pic of the coil, I can see that the factory resistor wire is still hooked to the positive terminal. It is easy to id as it is the rather oddly insulated, ugly duckling. I assume the red wire hooked there is for the p-tron module. I wonder about the black wire that is bundled into a common terminal with the ugly resistor wire. What's that one? Can you trace it out and id? I suspect it is the black wire hooked to your remote relay 'I' terminal. If you can confirm that, you can then remove it or leave it disconnected at both ends. It isn't needed with the p-tron in place.
Now back to that resistor wire. Your p-tron likes full voltage to the coil, but that resistor wire is supplying a reduced voltage. The reduction is needed for points, but since you no longer have points, you don't need the reduction. I suggest you replace the entire length of that resistor wire with an appropriate length of standard awg 14-16 gauge wire. By appropriate length, I mean long enough to make the run. The resistor wire originates at your firewall bulkhead connector and it is much longer than it would physically need to be to make the run. That extra length is what establishes the needed resistance for the points. You don't have to worry about that now. Just get it out of there. This won't magically solve all your troubles, but it should be done as part of keeping your electrical house in order.
Speaking of that, as you're discovering, loose and/or corroded terminals and connections between your battery and basically everywhere else are best avoided. They can be a major source of a vast array of electrical issues. Check them often and make improvements as needed.
For connecting a vacuum gauge, your best bet is to find a port that is coming straight off the intake manifold, rather than a port on the carb. This might be easier said than done in your case. Obviously, the hose feeding your brake booster is coming straight off the manifold, but that is a large diameter fitting. A vacuum gauge typically has a small diameter hose. If you don't have a dearth of smaller hose ports on your engine that are presently capped, you might have to get creative with a reducer so that a small line can be temporarily adapted to a large fitting, if that makes any sense.
Are you saying the extended wires are at the ignition switch in the dash? Those are the critical descriptor words I'm seeking.
I'm more of an automatic guy. I've serviced a few. Not so much the manuals. I can drive them fine. I just haven't messed with them much. How does it shift when you go through the gears on level ground and not pulling a load? Have you noticed any issues when you ease the pedal out to get rolling from a stop? The smell could be several things. Could be a slipping clutch. Could be electrical. Could be some type of lubricant cooking off of the exhaust. If you could have a grizzled wrench turner riding with you when the smell happened, his experienced nostrils could probably home in on just what was making the smell. Its tough to do much beyond make wild ass guesses from where I'm sitting. They haven't figgerd out how to transmit smells through the owl gorz interwebz yet.
So are you saying your coolant level will just go down over time, with no signs of an obvious leak point? You never see any drips from the hoses or the radiator itself? That's scary. Coolant doesn't just disappear without a trace. Its going somewhere. Better make sure it isn't getting into your crank case and mixing with your motor oil. That would be very bad.
