There's a reason that one port location has so many take-offs from it. Even GM uses such multi-line vac trees, just that theirs are vertical rather than circular. The size of the individual take-offs matches the amount of vac that is needed for the particular item. Hence, the power brake line is the largest and it is in the center.
Some items will work directly off of the vac level at the port as others will use a modulating device to get the correct amount of vac to a particular location (think "Thermo Vacuum Switch"). While others will use a "vacuum bias" (as in the evap emissions system) to control things.
Thermo Vacuum Switches will modulate WHEN a particuilar device is activated with relation to engine coolant temp. Ensuring the engine is at "operating temp" before a device is activated, which can relate to the evap emissions system and EGR, both of which do not operate during the basic warm-up period. Just as there is a small thermostat in the base of the air cleaner to close the "trap door" in the snorkle so that warmer air from the exhaust manifold "heat stove" gets into the carb rather than cooler/cold air from the ambient air supply. As complex as these systems might be, individually, they are really quite simple. They also need to work together for best desired results and emissions compliance.
Typically, that rear intake manifold port where the fitting is installed is somewhat consistent amoung OEMs, it seems. In some cases, some carburetors have a screw-in fitting on the back of the carb base plate for the power brake booster, specifically.
I will agree that the engine compartments did look a bit cluttered with the many vac lines and such, BUT if you desire to "make it look better", then follow the vac hose routing (decal under the hood and in the FSM, possibly) to make sure the hoses got to where they are intended from that ONE main vac tap. You can use more hose to loom the hoses together, for example, rather than having them route on the shortest route to their destination, for example.
I strongly recommend that you get a copy of the particular FSM to study BEFORE you start your beautification project. That way, you can study what is in the FSM and start to plot your course in your project. Then, use some bare welding rod to bend to use to measure the amount of hose needed in which particular diameter.
DO get quaity hose!!! They all might look the same, but can vary as to thickness and type of rubber. You do NOT want a vac hose that will collapse because of the vacuum in it!!! Indicate to the auto supply counterperson that you want ONLY OEM-spec vac lines and why. You can use reinforced rubber fuel line hose for the power brake booster.
There are also some other hoses under that hood that might could use some looming, too. Of course . . . pictures when done?
Enjoy,
CBODY67
