I have seen a few Berninas in original treadle cabinets, mostly flatbeds, I'm not sure about the freearm models. They have slighly different hand wheels to work with the leather belt, some are combo electical / treadle as well. I don't think it is that easy to convert the basic electrical models. With a bit of search you might find German made zigzag models in treadle cabinets, various brands. Some Singer 400 numbers came in treadle as well.