The stocks alone would easily bring $500.

The engraved gun is harder to guess at.

Unengraved, the gun would probably be worth $500 (without original stocks).

The engraving doesn’t detract from that value, but how much it adds depends on the buyer.

This is a gun that one of the high end auction companies (eg Rock Island ) would be ideal to consult. They often set up at good collectors shows (eg the Colorado Gun Collectors show every May). Give them a call.