I wasn't aware that there was a "pinger version" of the Puma 2 ever considered by the UK.
That one passed me by as well. I know that when the HC.1 was under development there was talk of selling the Puma to the Fleet Air Arm as a SAR cab to replace the Whirlwind. Unfortunately for Westland they were already delivering the Sea King, which freed up rather a lot of Wessex 3s to supplant the Whirlwind instead.