Need guidance testing vacuum with Mityvac

I have my HVAC box out of my 97 to change the heater core and the evaporator. I want to test the vacuum actuators to see if they are in good shape. I rented a Mityvac but and tested some of the actuators and with enough vacuum they all work but I want to know what the spec pressure should be for them to fully close to make sure my system is producing the right amount and that they actuators don't need too much to work as they should that the system can't produce what they need because they are worn out. I hope that make sense. Can anyone guide me here?

Don't know anything about the blend doors, but a healthy engine will produce 17-20 inches Hg. at sea level...

As I recall the minimum test pressure is 8 in/hg.

8 in Hg sounds good.