Tom R,
The wire from the Batt terminal of the regulator to the ammeter, though the meter, then to the battery is the main conduit for charging the battery and feeding the system with battery voltage.
If your battery had a marginal charge in it from the beginning, as the truck ran and the system pumped a heavy charge, the regulator might warm up, as well as the wires on the ammeter.
Warm and smoking are two different things. Could the gauge cluster have gotten moisture or bugs in it from sitting for years. The guts of this gauge have to pass all current.
With dangling wires and house light switches, troubleshooting the system might be questionable at best.
Did anyone notice what the ammeter was indicating when this happened. This little gauge will give you some basic info on the system health.
You need to get back to square one. Tape up stuff that isn't being addressed right now. Take one area at a time, verify it and scratch it off your list. If the ignition system is working and the truck starts, mark that off. Move onto the charging system. It must be a logical progression or you will end up going in circles.
Stuart