Ignition switch "run" output, alternator "blue" field, VR IGN terminal and "switch" side of ballast should all be the same, within 3/10 volt of the battery, measured with key in run / engine stopped
Alternator output stud and battery should be within 1/2 volt and certainly not more than 1V when "hard charging" IE battery down a bit or lots of accessories on
Coil + with key on / engine stopped will vary a lot, somewhere from 8--10V
Coil + "when cranking" should be 10V or more and "same as battery"
Coil + when running varies a lot, usually over 10V and 12V or less