My first starter check is remove the end cover and check the brushes. If any brushes are worn completely down, a very inexpensive replacement set might be all that is needed. Here cars tend to cover long miles with infrequent use of the starter. And I try to keep the engine in a state of tune, plus pumping some gas first, for an almost instant start. Even so I do not expect a starter brush set to last 150,000 miles. Your driving routine could make this far less. good luck, Bruce Roe
Whatever you do here make sure you convert it to a high torque starter. This hot start issue was quite common with large GM engines back then. Starter heat shield can help also.
My first starter check is remove the end cover and check the brushes. If any brushes are worn completely down, a very inexpensive replacement set might be all that is needed... Bruce Roe