As you say, there appears to be a striking variation between ambulances, and hearses. If you go through the Societies membership there are a lot of "holes" when looking for certain models. Try and find an early 60's C/B or non military Superior Pontiac ambulance. Not a surprise given how many were used. None of the vehicles from the 50-60's that served Calgary survived.
I feel EXTREMELY fortunate to be able to tend my cars, and will do my best to pass them on to caring souls when the time comes.