Rough-idling 360, can't figure it out!

steady vacuum >20 in? concentrate on ignition of you say the timing light pulses are erratic. Id put the points back in and try that instead of the pertronix just to isolate that piece. I had an erratic idle on my 4 banger and it turns out the carb idle circuit was full of crap E10 California gas jello. felt just like a vacuum leak too.