Why a 16-inch Kongō rebuild would be a radical compromise

Could the Kongō class have been refitted with 16-inch guns between the wars?

Only with radical compromises such as fewer guns and major structural work; it may be physically possible, but it would not be an advisable modernization.

The answer argues that the Kongo hull could not comfortably retain an eight-gun 16-inch battery because of beam, strength, and barbette constraints. Six guns in three twin turrets might be physically possible, perhaps with two mounts aft because of the fine bow. Japan's existing 16.1-inch production for the Nagato class removes the need to invent an entirely new calibre infrastructure. Even so, the structural work, cost, and treaty consequences make the conversion technically imaginable but strategically inadvisable.