Without a picture, I will take a stab at what I think you are asking. 1.The T fitting-you said one side goes to the booster. This might indicate that it is a fairly large vacuum hose and the other side of the T could be for the PCV valve. The 327 I have stored has a plug in the intake hole that I think you are referring to but the car does not have power brakes. Mine has the PCV hose connected to the rear of the carb-2 barrel.
2. Mine is a manual transmission but the tube going to your transmission is for the vacuum control modulator, I am fairly sure that is the correct term. It also has a small metal line that is connected to the vacuum advance via rubber tube.
3. The only thing under and behind the distributer that I see is the oil pressure sending unit, a bolt hole in the manifold for the coil mounting bracket, and the distributer hold down bolt.
I don't know if this helped since I am trying to visualize your description and comparing it to my 327. If not, sorry.