I have a Joe Montana signed 49ers helmet that I could use input on. 

Background on how I obtained it:  My Uncle was with a company that sponsored an NFL team.  Occasionally he would get to travel with the team to away games.  One such game was in San Francisco during the late 80's or early 90's.  He received the helmet on this trip and he gave the helmet to me as a gift when he came back. It has been in my possession since. I cannot verify myself that the signature is real, as I was not there but he assures me he was when Joe Montana signed it. I do not have any authenticating documents to go with it.

I am looking to either sell the item or at least know what its worth. 

My questions:

1. Should I look into getting it authenticated? If so, what is the best method for that?

2. If I were to sell it, what would it be worth? either with or without authentication. 

Pictures attached.

Appreciate any assistance,

Pete