I'm going to second your motion about a european player, but I'm going to change players and go with Kasasev. The main reason being, number one, I've seen him play and I haven't seen Saric play, and number two, he's a better shooter and the Kings need good perimeter shooting from their SF. Both players have similar traits. Both are very good passers, and both have excellent court vision. Both have the same question mark, and thats whether they can play defense in the NBA. All I have to go on is that I saw Kasasev keep Wiggins in front of him on one occasion, and I saw him keep Julius Randle in front of him. Not much, but its something to go on.
After Porter, there's no one at the SF position I'm interested in until you get to Kasasev. I only saw him in one game, but he really impressed me with his court presence, his passing, and his ability to hit the open shot. His BBIQ looks excellent.