I know its far out, but carefully check you battery cables. I have seen this type problem several times when the cables were corroded enough that they would pass enough voltage to look and seem OK, put would not pass the heavy current for the starter and?or Solenoid, In these cases, the cable looks fine externally, but is failing under the insulation. Otherwise, get your voltage meter, and start backward from the starter. One good thing about a gasser, just about any good mechanic with truck experience can work on most problems.
