[MJN]

Your brake booster should have a constant source of vacuum, if it is not plumbed to a fitting on the back of the carburetor base plate then it should be connected to the intake manifold. There is a vacuum port behind the carburetor that can be used for vacuum for the brake booster. Looking at the vacuum schematics in the service manual there shouldn't be a connection to the brakes for this switch. The main vacuum source should be coming from the carburetor to the TVS.
If you remove the TVS and install a 90-degree fitting as shown your coolant will all be lost. The TVS uses the coolant temperature to control the vacuum to the different ports for EGR valve, and fuel evap system.- its a thermal vacuum switch to control parts of the emissions system. If the TVS is not used then remove it and plug the water neck with a pipe plug.