Starter Voltage while cranking

Hey guys, 75 duster with a 416 stroker and new mini starter from 440 source. The car has 1300 miles since new engine and starter, and the starter started randomly clicking at times (pulled it out and contacts were bad). The starter/alternator "Guru" in our area said this could have been caused by a low voltage situation to the starter. It has since been rebuilt with good known contacts and plunger (probably originally was made in china i'm sure). Now, before I put it in, I checked the battery for giggles to make sure there is no low voltage issues, turns out it was 12.6 volts with the car sitting for about a week. I checked the end of the big starter lug positive cable, same voltage, 12.6, and the small lug wire when key is turned to start, 12.2 volts. So after I installed the starter, I checked it again. While cranking engine, the big lug at the starter showed 10 volts and the small lug showed 8 volts under load. Nothing else was using electricity except my msd ignition box. The car cranked fine, not like it was struggling or anything. So, my question to anyone who knows is, are these voltages under load what I should see at the starter, or are they in fact too low and could have been the culprit for my new starter's contacts failing? Also, the car has been totally rewired, so I don't have any crappy old wiring I'm dealing with. The main thing is I just wanna make sure that the starter is getting the appropriate amount of voltage under load so that it lasts this time. Thanks in advance