Believe in the GM HEI ignition now?

While I promote the HEI, especially for those with points, I think there are too many variables to claim that HEI improved your idle. Sometimes changing the Mopar ECU helps, not because the ECU was bad but the ground screw got a better connection in the process. I am sure you also re-timed the distributor.

I prefer the junkyard, not just because cheap, but because that red/wht cable is a factory GM part that looks better and you can easily unplug. Someday, you can control spark timing via that 2nd Metri-pak connector, with a Holley Commander ECU or others that support the 8-pin HEI module.