I guess that you are only after a PN16 valve if you want cast iron. I work in the steam business, so I know that Spirax Sarco do a range of bellows sealed stop valves.
Look at several websites and you may find what you are looking for:
Jordan
Fisher/Bauman
Masonealan
Kammer
All of these companies have Bellows valves. Jordan Kammer and Bauman offer Bellows in several models.