Heater & A/C control

Not much in the way of a response to my last question... Let me try a new one.
I am working on a '72 Duster. I have a '75 Duster parts car. Both are a/c cars. The HVAC control is different between the two. The '72 has a fan switch, 1 heat lever and push buttons that control the a/c. The '75 has 2 levers, 1 for heat and 1 which controls the a/c modes.
Is the '75 a better set up? As I can use either one I would be interested in finding out why the change.
Thanks,
C
PS, if you missed my post earlier; I would love to see some pictures of an aftermarket a/c system inside the car...