Using Nelson's treaty margin for speed and better guns

How could Nelson and Rodney use their unused treaty displacement most effectively?

Improve the 16-inch gun and add machinery for a third shaft, potentially raising speed to roughly 28 knots.

The proposed redesign changes the 16-inch gun from the historical light-shell approach to a heavier projectile. A somewhat longer barrel and greater elevation would improve range while keeping the existing calibre. Nelson and Rodney also sat below the 35,000-ton treaty ceiling, leaving roughly 1,200 tons for machinery. Extra boilers, a third shaft, and another turbine could raise output to about 66,000-68,000 shaft horsepower. The rough result is a 28-knot battleship that retains the class's core protection scheme while gaining a more effective gun and a useful increase in operational speed.