I have some of their movies, my favourites being Fog Island starring the wonderful George Zucco (and Lionel Atwill), and The Lady Confesses with the lovely Mary Beth Hughes. Both films were from PRC and released in 1945. I would buy anything with George and Mary Beth on blu-ray.
You should check out the Great Flamarion and I Accuse my Parents (if you havent already) they have Mary Beth Hughes in them. I used to have the Alpha DVD of Great Flamarion but found an import DVD
I have a lot of the Alpha mysteries like The Sphynx, Sinister hands, 13th Guest, Wayne Murder Case, Murder at Dawn, etc They are fun little lazy Sunday type of movies