Double check the firing order and spark plug wires. You may have mixed them up. Check that the distributor isn't off a tooth too. A huge vacuum leak will cause similar popping, rough idle, super rich condition too. Some cam gears were nylon, well late 60's early 70's anyway. They would get brittle after around 15 years and strip the teeth off. The lucky had it happen at startup .... like me. I don't think that's your problem though. Start with the simple/ easy to overlook things.

Les