On your 1406 carb, the full time
(manifold) vacuum port is the LEFT (drivers side) port.
You said earlier "Distributor vacuum is connected to the left side vacuum of the carb and my vacuum gauge inside on the column is connected to the right side vacuum port on the carb."
If the vacuum gage is set up this way, and the left and right references are correct, you have the vacuum gage set up on the ported vacuum port. This will not give a correct reading at idle!
This also would mean that the distributor's vacuum advance is on the manifold vacuum port- this would be fine... but I have the feeling that your references are as you face the engine, not as you sit in the car. If this is the case, try putting the vacuum advance line onto the drivers side port and see if the vacuum at idle improves. You will need to lower the curb idle if it was on the ported side before.
This can be confusing- you (and the others here) need to refer to all "left" and "right" as if you were sitting in the seat of the vehicle, OR specify "as you face the engine or carb", or words to that effect.
Better to just say "drivers" or "passenger" side, that way there's no question as to what side you're talking about.
But bottom line, if nothing else is said
, "left" is always
the drivers side and vice versa.
BTW, your 1406 is a 600 CFM carb.