HEI Upgrade but No Spark (kinda)

I would say "simplify the problem" and "build a jig."
What is the absolute minimum you need to test components and make spark?

1...Mounting/ heat sink for the HEI module, and of course a working module. Mount it flat, remove the protrusion from the case, and consider using thermal compound.

2.....Distributor. Maybe the conversion is the problem. Examine the reluctor for strike damage and set the gap, checking it with vacuum pumped up so the gap is proper and so you can check gap change. Make certain the reluctor is not striking the pickup, nor that the bushing play is so much that it moves over, increased the gap and won't trigger. Suspect the 2 wire pickup connector. they can be troublesome. Must be clean and tight fitting.

3...Coil. for testing, coils are not finicky as to type, but of course you need a "good" as in proper functioning. When I ran the 4 pin HEI on my Dart I used the factory stock Mopar coil!!!! (And no resistor)

4...Spark gap. NEVER test or run ANY electronic ignition with an open coil connection or with a plug wire pulled loose. This creates tremendous spike/ high voltage energy which feeds back in the coil primary circuit and can damage/ destroy the module. "Rig" a spark gap at the coil tower and use WIRE core wire. THE COIL CASE is NOT the coil ground (if metal) The NEG battery (car body) is where you want to ground your test gap.

5....Wiring/ connections. Make CERTAIN the module is grounded at the mounting bolts at the heat sink, TO THE BATTERY. The module + and coil + of course go to battery + SUSPECT A TACH WIRE. Disconnect ANY other wire going to coil NEG other than the module wire, and disconnect any radio supression cap "for now" for troubleshooting Might even want to measure some voltages maybe you have a simple "bad crimp" or wire splice.