Probably is a Broadway Grade 1 Trap gun if the rib measures 5/8 inch. If it is truly from the original owner and has never been shot and he has the box and the hanging tags and receipt, etc it will bring a premium price as it will have some actual collector value.
If it has been shot and does not have the box, etc, but is in 99% plus condition, then maybe a high end price of $1795 if it has 32 inch barrels and $1595 if it has 30 inch. This is a bad time of year to sell trap guns and it is just a very bad year to sell them in general --- so it would not be easy to even get the prices I listed without the gun really being nice.