I've come across a few Rem UMC 12ga Sureshot Kleanbore #8 shot, ribbed paper case. Are they worth anything or should I just shoot them up.

Do not shoot them. Those shells are from the late forties/early fifties most likely. They were not trustworthy in the late sixties in some cases depending on how they were stored.

For information. These could date to the early 30's. My " Jobbers' Wholesale Selling Prices to the trade..." catalog dated January 1, 1930 lists Sure Shot shells.