Never run without oil, never over heated and worm gear only worn on one side. That being the case, perhaps shaft of distributor is bent or it was loose and held down of center. Remember the noise started after the fill up and two cylinders full of coolant, dogging the 3 & 5 and perhaps spinning the 7 by uneven downward pressure on crank. Even after the distributor was worn it worked fine at even RPMs and coolant being ingested slightly for 1000 miles tick became knock only after that. So the bearing spin may not be anything to do with distributor filings. Remember the "knock" is not heard over an idle so it's not like there is much movement, as if so it would be louder upon increase in RPMs and a double knock, one up one down.
