Confusion!! The title talks about B&W, but the films mentioned in the body of the original post are color.

There's only one medium format B&W film faster than ISO 400: Delta 3200 (which is really about ISO 800-1000 equivalent, but pushes extremely well).

Fuji makes a couple ISO 800 and 1600 *color* negative films, and Kodak makes one ISO 800 (Portra 800), but none of those are B&W; all C-41 B&W films I'm aware of are ISO 400.