What is the value of a belgium browning 12ga over under lightning 63466 s6 ex cond never fired?

This gun was made in 1966 Superposed shotguns are very collectable when in top condition. Values have a wide range due to so many variations and grades of the Superposed and other Browning Over/Unders. Value is too difficult to be accurate without seeing the gun. Condition which includes the amount of original finish and original configuration will determine value. Recommend taking it to a gun shop for appraisal.