If you’re seriously looking to sell it your best bet is to search gunbroker for recent sales that show the Sold price (not just asking price)
the facts you have the (I assume) original box and it is 30” are in your favor.
Ruger is reducing more every month (if not week) the repair work they do on all their past shotguns and soon replacement parts will be getting scarcer by the week also. Those are the main reasons I sold my 28ga (28” pistol grip) and 12ga “Woodside”. The former went to a very, very serious quail hunter and the latter went to a collector who does intend to shoot it.
again, your best bet for realistic value will be the actual “sold” prices of recent sales on sites such as Gun Roger etc