BBD question.

That carb looks like one of mine, hole only in one barrel.
Pop those limiter caps and either hook up a vacuum gauge and/or tach and adjust the mixture screws for highest reading you can get.
When I got my 83 D250 (318, but would apply to any engine) it had plugs over the mixture screws that were in a recess. I removed the plugs so I could access those mixture screws and got my best readings and performance with them 3/4 turn farther open than they had been set at the factory an those plugs driven in. Better mpg too. Your results may vary. All engines don't run their best with exactly the same settings as another.
I still have the original intake and carb from that engine. I had later swapped to a 4 barrel intake and carb. For what it was that engine didn't run too bad with that carb, it's a Holley 2280.would directly bolt on in place of a BBD.
If I don't get to the manifold carb and cam swap on my fury, I will probably put a kit into that carb and use it when I delete the lean burn system for now.
It's original carb is a 2280 that lacks a hose barb for a vacuum advance can.