I agree with all of the other posters, you have to book a 1 BR at any DVC resort in order to get a king size bed. That's one of the reasons many DVC members book 1 BRs despite the fact there are only two guests in the room.
Won't be possible at OKW, the headboards are not attached to the wall with matress sitting on separate metal rail/frame like what is typically found at most hotels. OKW queen beds are rather heavy all around wood framed style and attached to headboard.