The charcoal grate for the kettle is now the top rack for the wsm portion (kettle charcoal grate is 22inchs). I had to cut the top tabs on the straps that hold the top rack in the wsm for the kettle to sit correctly on the wsm barrel. I haven't tried yet but the bottom grate in the wsm is slight smaller than the top so it should fit fine.
Also I can't take credit for the setup. Eric palmore, brian Moriarty, and Larry beercan Fischer have been doing this for years with different size drums, kettles, and wsm.