Not getting 12 volts to coil

speaking of voltage drop, is a 1.7 drop on the positive path of the alternator while cranking excessive? An alternator said that drop was normal due to the starter..What's normal? I have a 70 'Cuda and could not get this kind of depth on an e-body site. I'm getting ready to check my ignition switch, as voltage is only 9 on the ballast resistor with current coming through the bulkhead connector on cranking, which shows up at the coil +.