Tiger as a fast specialist rather than a battle-line ship

Would rebuilding Tiger be a better use of resources than retaining older British battleships?

Potentially. A very fast Tiger would have specialised utility, while old slow battleships would be dangerous to retain in a modern battle line.

A highly modernized Tiger could be more useful than retaining older Queen Elizabeth-class ships in the battle line. Replacing early coal-and-oil machinery with later oil-fired small-tube boilers could test how much speed a reconstructed battlecruiser might gain. A 35-knot specialist would offer cruiser protection and deterrent value while generating practical knowledge for later designs. Slow non-treaty battleships, by contrast, would be outclassed outside the Atlantic and could become liabilities if asked to stand in a modern battle line.