I am not sure about the filters, but with Retinas with the lever wind on the bottom, there was an adapter that fitted the tripod mount on the bottom and fitted into the black plastic in the center of the bottom plate to make the tripod mount in the middle, I have been using Retinas for years, love them, and I have never seen one, they seem to be as rare as hens teeth, I just manage with the offset tripod screw, as for filters, I use small old filters or cut down Cokin filters cut down carefully and good old blu tak, works a treat,
Richard