I have just purchased a Lefever 20ga SXS and would like some info about it. The SN on the barrel and receiver is 67669 followed by DS. There is also a 2 stamped in the receiver near the SN. On the bottom of the trigger guard assembly is stamped Patented 1872-88-90-94-1907. The butt stock appears to be original with a few light dents/marrs & has original butt plate. The checkering on the pistol grip is very light/worn. The blueing on the barrels is good but at the receiver the barrels and receiver have very little blueing left. Anyone have an idea of age and value?