So this is probably beating a dead horse but...
this valve is stock for '70-72
The all metal type is stock for '73-74. The one currently in your car looks aftermarket, but the originals for those years are pretty similar.
Unless you get the non-AC heater box you'll need to keep the valve. The non-A/C box has manual vent handles, the A/C box does not. So, if you disable the valve and don't switch boxes, you'll find that you always have some amount of heat in the car. And at highway speeds its practically like having the heater on.
I've become pretty familiar with this phenomenon because my A/C doesn't work, and I lack a heater valve cable. So I zip tie the valve shut in the summer and open it in the winter. Sadly, in the spring and fall I have issues, since I need the heat for the defroster but don't need it later in the day when its nice and warm. But even with the blower motor
off and the valve open, you get a fair amount of heat in the car.
One of these days I need to get a heater valve cable, fix the vacuum operated heater door and sort out all of my vent tubes...
