Well apart from the Jetting being incorect (wrong fuel/air correctors or fuel jets worn) or float level being too high, there should only be an idle mixture adjustemt, which on pre emission carbs is usually very easy to adjust "by-ear" so to speak.
(assuming the rest of the ignition system is in good working order as is the engine
)
As a first step ,after checking your air cleaner is clean and warming the engine up, adjust the carb at Idle using the Fuel idle adjustment screw. This adjustment screw ill be found on the side of the carburetor . May need to look at a Carburetor diagram for this carburetor if you do not know where it is.
Slowly "Tighten" the screw clockwise (so it goes in and reduces the idle fuel flow) until the engine runs rough (lean) and then "untighten" the screw until the engine runs rough and does the "POM POM " sound of a rich engine. Then retighten the srew about mid way between the two points (lean and rough) should only be 1-2 turns between lean and rich.
NB when "untightening" the screw from lean to rough the engine should go through a run well stage. But continue on to rich so you get a better idea of where the optimal adjustment point will be.
If this does not solve the problem then there are other forces at work such as jets, float level.
For info
If the car has a more elbaborate setup such as the twin Dellorto carbs on the Alfetta Series of cars then a
Gunson Colourtune in conjuntion with a carb balancer works wonders. ie treat the engine as a single cylinder engine and adjust each idle mixture screw in turn using a Colurtune spark plug.
and knowing little about the subject.
as the car is very heavy and was known for its thirst 
