Good question.

I don't know what you mean by "traditonal calibers" but I'll have a first crack at it until
you qualify the meaning. Are you thinking "English" traditional or just pre 1930 calibres ?

My personal preference would be
275 Rigby (7x57), 375H&H and a 500 Nitro in a double

I've shot game with all of these and they all work with the 375H&H being able to do the
275 Rigby and 500 Nitro work if it's in your hands.

IMHO, this combo have enough bullet weight variations to provide a range
and 500 Nitro gives alot more punch than a 450/470 and enough punch all over for elephant
but without lugging TOO much weight around.

CHANGES - At the lower end I would PREFER a 30 cal as I believe 30 cal is
far superior to 7mm. However I didn't know if "traditonal calibers" included 30-06
or not.

500 Nitro