I can't help with the cross-referencing of parts I'm afraid, but it might be worth giving DA Motors a ring. They're a specialist Fiat breakers in Essex, and I know they've got several Multiplas breaking. Tel. 01268 767424 (John or Dave). I'm in Wiltshire and finding a breakers with a Multipla is like looking for rocking horse poo, even when I tried places in Bristol.
Before anyone asks, I've got absolutely no connection with DA Motors. I found their number on Yell.com and I'm a satisfied customer - they were helpful guys, know their stuff, prices and carriage rates were very reasonable and all the stuff I bought was in good nick. Can't ask for more than that!