Why HMS Dreadnought is a poor conversion candidate

Which British battleship would be the worst hull to convert into a significant pre-dreadnought design?

HMS Dreadnought, because she is comparatively small and offers little room for such a conversion.

The proposed conversion asks an existing ship to reproduce a significantly earlier arrangement. Among British ships, Dreadnought is the worst starting point because she is small and offers little room for the required changes. French alternatives might be even less suitable, although the comparison here is limited to British ships. A famous hull is not automatically an adaptable one.