If you are getting 7.5 not running and 14 running, that is your problem....... you are getting backfeed from somewhere or the ballast resistor has given up the ghost.
max out of the resistor should be 9 ish volts, if you're getting 14 you will or have burnt up the new coil and or points.
The wire coming from the starter's "I" terminal supplies the coil with a full 12v while cranking to aid in starting..... you need to hook that back up. Once the engine starts and the key goes to the run position the ballast resistor or resistance wire supplies the coil with 9 ish volts. The coil isn't rated for a full 12v all the time.
NAPA sells a ballast resistor for the old MOPARS, I've used them in the past and they work great.