Have you tried John knibbs http://www.airgunspares.com/store/category/77/599/BSA/Martini/
they do talk about international shipping in their t&cs. And although they don’t have mkii stock in er... stock right now, it may be worth a chat.
I bought a Martini ISU stock from him and it was in brand new condition. Or at least it was till I modified it to have an adjustable cheek piece (couldnt bring myself to do it to the original one)
J