73 valiant no spark from coil

Hey guys I got a 73 valiant 4 door with 198 motor. She cranks but no spark from coil, only occasionally when I turn back to off position I get 1 late fire that causes a small back fire out of my intake. I replaced the ignition coil, ballast resistor, starter relay coil wire and ecu I'm racking my brain :banghead: :mumum::angry1::sad1: but can't come to a solution.
Here's a little list of things
-At the coil with the key in the on position the coil reads 4.3-4.8 volts when engine is cranked it only jumps to 8 volts- one problem
- Ballast resistor seems to be giving a correct resistance reading.