Poor Elfin

I am sorry to be negative but I think anyone so specific in their requirements, is likely to look at a cat as an item rather than a pet.

And as the Declawing...I bet £10 that he is declawed and neuter together at six months (though I really hope I am wrong)

I wouldn't let him go to that family, if you have any sway with the charity use it and keep him until his real family come for him.