Sounds like you have 2 separate problems. Starter & voltage regulator. I am not familar with the regulator you described. On my '68 I replaced the old Bosche with a new solid state regulator. The starter is a common problem after a long drive when it gets over heated. This is solved with a "hot start relay" that is a simple installation.
There are good discussions about the hot start relay on the 912 registry BB.
