Brother Day is exactly right in his assessment. DH Parkers are very common. The gun's extra value, if any, is solely in being a 14 gauge. As far as "restoration", were it my gun, I would simply send the barrels off to Dale Edmonds to have the dents removed and be redone in black & white, make sure the incorrect fore end fits properly (whether you have it renumbered to the gun is up to you...) The gun will be worth the same then as it would be if you had a full blown restoration. I have lots of D grades. Only two are "fully restored". I regret restoring both of them but they do look nice.
Good Luck with your gun.