Alaska-class 14-inch gun counterfactual

What would change if the Alaska class carried six 14-inch guns instead of nine 12-inch guns?

Very little. The older 14-inch guns had about the same penetration, and any schedule gain depended on finding usable guns, turrets, and mountings.

Replacing the Alaska class's nine 12-inch guns with six 14-inch weapons would make little difference because the older guns had about the same penetration. Reusing an existing weapon might have brought the ships into service sooner, provided usable guns and mountings were available. Texas and New York still carried their weapons, Nevada still needed hers, and Oklahoma's turrets might not have survived Pearl Harbor in salvageable condition. Spare barrels could have existed, but barrels alone would not solve the turret, salvage, and installation problem.