Current Cook just doesn't have what it takes to hang with King, sadly, RS or not. Only way for him to beat King is if he has help, from Marco for example.
But Zoro vs Kaido? That would rock the world. Just like some people here, I have also lost interest in Luffy vs Kaido at this point of the story. Zoro looked waaaaaaaaaaaaaaaay more impressive than everyone in Roof Piece, including Luffy and all his power ups. Just gimme Zoro vs Kaido and ZKK and we're eating good.