I have a shotgun that I got from a neighbor several years ago following his father's death. The son knew nothing of the gun and found while cleaning out the house. 

 

It is a single shot break action, the only markings ar "IB 412" on the bottom of the receiver and the butt plate says "stevens".  Its 12 guage, 30 inch barrel.

 

I have no intention of every shooting it, however, would like to get it to a functioning condition and need a few parts.  Any ideas?

It may be a Beretta Model 412.  The butt plate from a Stevens rifle/shotgun stock.

Nope, it's a Stevens.

Are there any markings on the barrel, like gauge or shell length?

Wait for the next gun buyback and turn your profit into a decent firearm, because it's "THE NEW JERSEY WAY".

No markings on the barrel, it has almost a dimpled finish