Possibly, but you said you have power to the coils so your black wire in your harness is energized.
I agree that all plug caps are unlikely the culprit. You can test the plugs and wires. I wouldn’t really replace them if they test good but I could be convinced.
To test the caps I would unscrew them from the wires and stick your multimeter leads in each end on ohms. Should be about 5k if they’re 5k ohm caps, which they should be. For the wires, stick your leads in 1&4 thusly:
I don’t know what readings you should get for the 650, these numbers are for the 550. Should be somewhat similar and 2&3 should be about the same.
But again, please answer this question. Have you tested if the spark units are getting 12 volts?
Lastly, are you sure your kill switch is set to RUN? Test that you’re getting 12 volts to the kill switch and out from the kill switch. I’m guessing yes, because you said you are getting 12 volts at the coils, but I want to be sure.
Also, post PICTURES! I want to see your multimeter at the spark units, coils and kill switch showing 12 volts.