Those Kodak Ltd. (GB) holders are very nice. But hard to find. I have two. I like the fact that they have metal rib lock plates, but the end flap is more delicate than the Eastman holders. There are Eastman whole plate film holders out there, but they don't come up for sale as often as I'd like (I have 5). In general the Eastman holders have been in worse shape than the Kodak GB holders I've found. And yes, there are probably more plate holders than film holders for sale at any given time with this format.
My Gandolfi was clearly designed around the British Kodak holders, but the Eastman holders seem to work fine. I just lose a bit of the image area on the flap end of the holder.