350 Engine Backfire through carb follow up

Guys,
Some time back I had asked for some input on a friends 360 chevy engine that is in a 69 camaro that was backfireing through the carb.
I had some good suggestions from you guys and most all of them were looked at, but found the real problem finally.
My friend had a Mallory Comp 9000 distrubutor on the engine, supposed to be a decent distributor, we thought.
After checking just about everything we could from compression to a worn cam lobe not finding anything, we finally decided to change the darn distributor and installed a bone stock HEI from GM. Well suddenly the thing quit backfiring through the carb and now runs great. Go figure.
I have also had trouble with Mallory ignition equipment and wonder how many others have had problems with it.