HEI Upgrade but No Spark (kinda)

^^Sounds like you were running a "one wire" alternator? That is a problem with some of them, them will not self-excite at lower RPM. I do not care for single wire. They are simpler, but require a much larger charge wire, as the voltage sensing is on that one wire, and it must have very low voltage drop.

What is an "Australian Ice" ignition?