Both HEI and Pertronix will convert/upgrade to no points, more dwell plus higher voltage to the spark.
Pertronix can handle a coil up to 40kV, allowing a .045 gap at the spark.
More than that is not required at below 3500rpm and stock compression.
HEI can go further than Pertronix, for higher rpm and compression engines.
But for a stock engine there is probably hardly any noticable difference in performance, between the two.
