In ALW's bio he doesn't mention ever considering to bring Paige over for Grizabella but I believe I've heard Betty Buckley say that she was worried during rehersals that (like LuPone in Evita) she'd be fired and Paige would be brought over. Equity was probably demanding an all American cast. Paul Nicholls was a bit of a star from Tommy so they might have tried to bring him over as the Rum Tum Tugger.
It is curious that Paige was only the third Norma in London. You'd think she'd have been more of a draw there than Buckley and would have got first shot at it. (Maybe she didn't want to be the one to follow all the turmoil with LuPone and also face stuff that she wasn't as good as Close.) Buckley on the other hand hadn't had a good role in a long time and was probably more willing to role the dice and step into the possibly difficult situation.