If the port you were referring to is the port at the top towards the right side on the rear of the carb, this is a port that is used to draw air into the choke heater on a factory set-up. It relies on the volume of air being drawn through the carb. Plugging it will not richen it up enough on a blown application. As far as Boost, you will not see any revving it up parked, only driving it down the road under load.
Hope this helps.