Lion was never a helicopter cruiser. Her appearance when scrapped in 1975 was nearly identical to appearance as first commissioned in 1960, less the parts pirated for upkeep of her two sisters during ten years in Reserve.
DeRuyter... I wasn't counting the Otomat SSMs as a significant ship conversion, just because I was accustomed to US & European navies slapping Harpoon or Exocet canisters on ships throughout the 70's and 80's without any significant reconstruction. I wouldn't have argued it with you if it would have been your third candidate.
However, further study of the 87-88 Jane's Fighting Ships and Combat Fleets of 98-99 shows that the former De Zeven Provincien, the ship that caused this question in the first place, lost her Terrier guided missiles when she was sold to Peru and had a big helicopter hangar and flight deck added, very similar to Tiger and Blake. Peru also switched names around, so that first the ex DeRuyter was named Almirante Grau, and then changed to Proyecto 01, then back to Almirante Grau while De Zeven Provincien started as Aguirre and was later renamed Almirante Grau, and then back to Aguirre...
aargh - what's next?