I would guess test it's value HERE in our Classifieds section: I'm no collector, but as mentioned above, if it's clean, it's should EASILY get you the same price as a brand-new (lawyer-safe) Single Six with both cylinders........ Yes, there were many made and many still around, but...........it's still an original, un-molested 3-screw. TEST IE HERE, you can always adjust the price to the market reactions here.
IMHO,
J