This appears to be a standard custard-type pumpkin pie filling.
I would recommend, as the method:
Blind bake your crust approximately 10 minutes, using rice or pie weights to keep it from bubbling up.
Mix all of the filling ingredients together well.
Pour filling into the shell, and put in a 400 to 425 F for about 15 minutes, then lower the temperature to 350 F oven until done, about approximately 45-50 minutes.
You will know it is done when the filling is barely jiggly in the center, but set at the edges when you shake the pan, or when it registers 180 F on an instant-read thermometer.
If the crust starts to over brown, line the edges with aluminum foil or a pie protector.
There doesn't seem to be anything special about this recipe, so using a more modern recipe which is accompanied by more precise instructions should not sacrifice anything.