Could light and heavy cruisers share a hull?

Could a navy build light and heavy cruisers on a common hull?

Yes, but the hull would need to be enlarged and strengthened for eight-inch turrets, making the six-inch version a more spacious and capable ship.

A shared hull was possible, but it had to accommodate the heavier turrets and structural loads of the eight-inch version. A hull built for the larger weapon would need more beam, and therefore more length, to preserve efficient movement through the water. The enlarged design could still serve with six-inch guns, but it would be an intentionally generous light cruiser rather than a minimum-size one. The tradeoff was excess size in the light variant in exchange for a common family able to support the heavy battery safely.