Marlin model 90 combination gun value?

[snowshoe2]

hi all-I have recently bought a Model 90 combination gun along with various other items. According to the Brophy book these were not actually produced for purchase by the public. This gun is .30/30 over 20 gauge. If anyone can tell me more about this gun and how much its current value might be i would be most appreciative. You can contact me at my regular email address: mwblohm@msn.com