Brad, the Longrange/Wildfowl gun was offered in 12 ga only. Most had barrels with either 30" or 32" and either full/full or mod/full.
The part that comes through the bottom of the receiver (lug) would have Longrange or Wildfowl stamped on it. If it is chambered for 3" it will have Chambers 3 Inches in an oval on the bottom of the right barrel's water table. Also most/some will have what is called a re-inforcing rib between the barrels water table and the for-end hanger (loop). It is easy to recognize as it will be a piece of metal that is "U" shaped.
Good luck and let us know what you find out.