http://fleetairarmarchive.net/Ships/LEVIATHAN.htmlThe last of the Colossus and Majestic Class Light Fleet Carriers was left incomplete until stripped for parts to repair a sister, then being scraped in 1968, up until this point she could have been bought and completed to almost any standard. UK proposals included re-engining them and turning it (and other available CVL hulls) into hybrid missile helicopter cruisers, but no reason why it couldn't be completed as a modernised CVS or LPH.
Apart from the Colossus and Majestics, UK options included Centaurs, Indomitable, Implacables to be modernised as Victorious and Hermes were, as well as Hermes and Victorious themselves. There were also four Centaurs cancelled at the end of WWII that you could whiff to a greater level of completion hence still have them on the stocks available for competition in the 50/60s. There were also the Escort Cruisers proposed for the RN in the 60s. Starting as Sea Slug armed vessels of similar configuration to Jeanne de'Arc (originally intended to have Masurca SAMs), or Vittorio Veneto with a medium range missile system forward and a hanger surmounting a hanger aft, before evolving into a series of through-deck designs with aft mounted Sea Slug, Tartar or Sea Dart in various locations, some even including medium calibre guns.
US carriers were either to large or too small (perhaps more limited by their cruiser origins) for what is being discussed but maybe other US concepts could be examined, i.e. a conventional version of the Strike Cruiser etc. I would be curious to see some of the Iwo Jima carrier concepts (including Standard) as I have only ever seen the sketch and tabulated data in Stewart Wilsons "Wings Across the Sea". Same goes for the carrier version or "Modified" Tarawa with its 50 helicopters and Harriers.