Carter BBD vacuum port

Hello, i recently picked up a 65 dart automatic with a 273 and a Carter bbd. The car has been converted to electronic ignition. I have been trying to tune out a rough idle. First i adjusted valves, they were all on the loose side. Set timing to 8btdc static, advance plugged. The car is pulling 16" vacuum at idle, and it's steady even with the rough idle. The idle screws were 3 turns out, and they don't make much difference until they're about closed.
What i noticed is that someone plugged the vacuum port on the passenger side of the carb body and have the distributor plugged into the vac port on the rear, which also controls the choke pull off. Is that a ported or non ported hole? If dizzy needs to be plugged into the passenger side port by the bowl, I'll probably have to replace this carb, it's plugged with a screw that's cut off