Pay close attention the keyboards. Do the keys look shorter than modern organs to you? In the past, especially during the baroque era, organ keys were very short which made proper organ technique essential; specifically, curved fingers playing in front of the black keys whenever possible, and no extraneous movement of the arms and wrists. Incidentally, Bach was one of the first organists to begin using thumbs to play the organ--prior to him, thumbs were not used.
The story behind this organ is found here, in Italian. Google Translate let me understand the basics of the story, but not much more: http://www.santagalla.it/index.php?indirizzo=Organo/Storia/storia.php It appears the origin of the organ is unknown. Here is the stop list.