US heavy cruisers become 15-inch Scharnhorsts

What if all US heavy cruisers became 15-inch-gunned Scharnhorst copies in 1938?

The US gains fast capital ships in cruiser slots, making raids and encounters with Japanese Kongos less risky, but pays in range, air defense, crews, and a new 15-inch ammunition chain.

Replacing Salt Lake City, Northampton, and Vincennes with 15-inch Scharnhorst-style ships would give the Doolittle Raid three fast capital-ship escorts. The force could approach Japan with less fear that Kongo-class battleships would catch it. These replacements would consume more crews and lose some of the range and antiaircraft qualities expected from American heavy cruisers. The US Navy would also have to create a new 15-inch ammunition supply instead of treating the ships as simple cruiser upgrades.