Although not exactly one of the choices you mentioned, I would consider re-barreling to 325WSM. A standard factory cartridge with goods bullets (Nosler PT, Barnes TSX) for heavy game. Dave Scovill did exactly this with an early Kimber. FWIW

Is life so dear, or peace so sweet, as to be purchased at the price of chains and slavery? Forbid it Almighty God! I know not what course others may take, but as for me, give me liberty of give me death! P. Henry

Deus vult!

Rhodesians all now