Kim did some really great covers IMO while with Charlton. They are different and unique and I think he gets overlook beside some of the more juggernaut horror artists. But if I am gonna buy a Charlton comic, some of these would be a the top of my list. His painted covers and the Ditko-esque colors make for a winning combination in my books.
My question is are any of the stories inside any good?
I never really thought of Kim as a horror artist, but those covers you post above show he has the chops. From my few discussions of Kim with fellow comic fans people either think he is a horrible artist or want to give him lots of love. He draws peculiar faces and his scratchy style will not be to everyone's taste. I quite liked his work on Yang/House of Yang. It is in the genre of martial arts books he seemed to have put most of his efforts in the North American comic book market.
He looks pretty good in black and white as this image from Deadly Hands of Kung Fu shows.