HMS Swiftsure and HMS Superb were in effect sisterships to HMS Blake, HMS Lion and HMS Tiger, as far as the hull is concerend.
To be more precise, and to perhaps add further clarification, Blake, Lion and Tiger were originally Swiftsure class vessels, and were originally going to be completed to the same exact design. They were more or less 100% finished up to the top deck, and about 10% finished on superstructure, when two things came about to change everything:
1.) The end of WWII and thus they became surplus
2.) The development of said RF automatic 6" gun turret, which actually promised a new life for these unfinished hulls
Thus, the ships were modified to best accommodate these new turrets as practical (the main limitation being the turret's weight). If they had been new-build hulls for the purpose, I'd imagine the Brits would want something closer to the U.S. Worchester class (which infact they did - the never-built Minotaur class which again owe their basis to the Swiftsure, along with the never-built GW96 missile-gun cruiser which Hood/PB did earlier in this thread).