Retune my entire carb after installing new heads?

Interesting idea, thanks! I hadn't thought about that possibility... but is that quantity of air really that substantial through .100 holes at 15" vacuum? The primary throttles are open further, at highway cruise, so I would think almost all the airflow would be going through those bores as intended.
But even if there is some pullover through the secondaries, how is that a problem? The cruise mixture is lean where it should be... and 71/86 jetting is not unusual.