If you look at the picture of N317Y it seems to have the skinny Sea King sponsons with pop out floats, rather than the broad S61NII sponsons. I was always under the impression that the S61NII had broader sponsons to give stability without having to plumb for and have the extra weight of the pop-outs. The Sea King needed minimum width for onboard stowage in the ship's hangar so pop-outs were the solution after the prototypes were shown to have minimal lateral stability.
I amazed to see the film of the KLM S61 not just land on but shut down during the abandon drill: just think of the OH & S cr@pola that would surround such an exercise today
Not that the pop outs did much anyway for Sea King/S61 stability, this was SS2 with a long swell:
