I think he wants to know more specifically about the boss kit itself.
Yes, some boss kits will fit and house the steering centre, but the teeth are wrong and hence when you indicate around corners it will remain constantly on (or not even on at all). So make sure the boss kit is correct.
As for the part number etc, not sure of exact details, but momo and nardi are your best bet. Just do a search on their sites or ask around.