The .357/.44 Bain & Davis originated from the Bain & Davis Gunshop in San Gabriel, California in the early 1970's. the conversion was written up in Guns & Ammo Magazine then.
I dunno if B&D are still in business.
Yes, rechambering a 9mm cylinder to .357/.44 B&D is rather easily.
Loaded carefully, it should come close to .357 Maximum ballistics. However, I don't know if it will have the same problems with gas-cutting the top strap as in the Ruger .357 Maximums.
John