You may already know it, but the "side arm" for the Miranda Sensorex series lenses does not mate up with the Sensomat series bodies (which are similar to the DR and other early models). The lenses will mount on both bodies, but the side arm on the lenses is NOT the same. Bottom line: If someone offers you the lens from a Sensorex, it can be used.... but you probably won't be thrilled.
I have a Miranda waist level finder near mint in original box that I could part with. It fits the Sensorex, but I don't know if it fits the DR or Sensomat series cameras.