The Andrea Doria was a rather weak fast battleship, inferior to the ship against which they would likely have been deployed, the Queen Elizabeths, for about the same cost of a brand new Littorio class.Captain Seafort wrote:
Everyone was doing it, to great effect - the Italians turned the Andrea Doreas from next to useless to modern fast battleships, the Japanese turned the Kongos from battlecruisers into fast battleships, the UK transformed Renown and gave the QEs a new lease of life (especially QE herself and Valiant), and the US rebuilt the near-useless Standard-type Pearl Harbour wrecks into the battle line that won Surigao Strait.
QEs upgrade was far less extensive,at least for the main machinery and armaments.