The black valve cover engines were definitely -3 (Special High Performance - more in a bit). There was the 'lil Red which was supposed to be -3 (some were stamped HP) but it had chrome valve covers. Most of the Super Coupes I have seen had the black valve covers, but 2 of them I checked were stamped HP not -3. Then there was was the 300. It had blue valve covers and chrome looking oval sticker on the left valve cover reading "Premium 360". All those engines I've torn down or inspected had all the -3 parts but were stamped HP. All the above were the '69 up 340 cammed engines. Then there was the same stamped HP blocks that had the 252 duration "2bbl" cam option code E57.