Just remembered - the camp site we use at Fowlmere, when we go to Duxford, is run/owned by Tony, who used to be on SAR with 202 Sqn.
All being well, I hope to be going there again in mid May, to take my daughter around DX, so I'll ask him what he knows about the Wideawake deployment, and when the larger intake filters were added to the Sea Kings. You'll need to remind me nearer the time though, so I'll remind you to remind me to .....
As for numbers, there weren't many Sea Kings to spare, but at a guess, I'd say there were possibly two sent down there - one for 'Ops', and one as a spare, in case of down time on the main chopper. It wouldn't surprise me if only one was sent though.
EDIT:- just noticed, in the pic of Wideawake - on the smaller rectangular apron in the foreground, there appear to be two helicopters which could be Sea Kings, although one looks like it might be a Wessex, which were still used in the SAR role at that time.