The only wire at the alternator that should have 12 volts with the key off is the big main black one to the stud.
The other two (blue and green on my '71) are field wires from the regulator.
I think the reason the car won't shut off when you turn the key off is because the coil circuit or the ballast is still gettingpower from somewhere.....MAYBE the same place those other alternator wires are getting it too.
Start trouble shooting the ignition switch,ballast and regulator circuits...I think there-in lies the problem.