I have been recently put in charge of selling a friends fathers gun collection. this model 280 skb made by ithaca is one of the guns, I know little about this one. I need your help. It is a 20ga. SxS straight english stock. quail engraved on both sides of reciever with a lot of other engraving, gold trigger. what is the value of this gun it's new in box with papers unfired? did they make different grades of this model 280? Thanks in advance.