I think you will need one of my three earlier suggestions. The diode is trouble free. It has polarity so it must be installed the correct way. If you install it wrong, the alternator won't work. There is no damage. Hook it up the other way and it should work fine.
There is a possibility that the solenoid connection would work but it is doubtful. Usually when the switch is turned from start to run, the alternator is not spinning fast enough to start.
I have a Ford 901 that I put the normally open switch on. It works fine but sometimes I forget to push it. And occasionally when I idle it down too slow, the alternator drops out. I like the diode option the best.