The .550mag in a CZ 550 mag. how appropriate.
The largest caliber you can put in a strait walled 2.9" Weatherby case is a .550.
Just like a .458 (or .470) in a .375 magnum based case. No visible shoulder and head-spaces on belt.
The .550 Express is the little sister with a 2.5" or 2.65" case. Will fit in standard Mauser 98.
http://www.550magnum.com/