Like the convoluted thread the other day THIS CAN easily be wiring / connector problems. Check them carefully, visually, and work them in/out several times. Check "feel" for tightness
One VERY popular problem used to be the distributor pickup connector.
Personally I run HEI. At the time I tore the car down for paint, I just had a simple 4 wire HEI mounted on the firewall. You can ALSO hide these in a gutted Mopar ECU case.
Even without running a hotter coil, you can run the FACTORY coil and no ballast resistor, and get more spark out of them.
