Ok...I think I've identified the burned up pigtail coming off the back of my HEI.
Again, this is an '86 K5 Blazer, with the weird-ass 5-pin ignition module. On the back of the HEI enters a small pigtail/wiring harness. It plugs into 3 of the pins on the ignition module.
Does this go back to the Electronic Spark Timing / Control? I know it shouldn't have a real "ECM" because it was carbureted, but I believe it does have the EST. I don't know to what degree electronics played a part in the original Quadrajet. That carb is off the truck and it's running an Edelbrock Performer 600cfm. There ARE a couple of unused wires/connectors that end up in the vicinity of the carb that I assume would've been attached at some point.
If the harness I'm referring to does indeed go to an EST unit, is it necessary to get the truck to run? Can it be bypassed in any way?
The pickup wires connect in between this connector and the actual ignition module. A picture of all the parts can be seen here...