I' m going to say .375H&H, the .338 win mag or lapua is great too, but I really like the .375H&H. Your .30-06 would do it fine, but it would be best to get something bigger, since you' ve only been able to get one once every twenty years, I don' t think I' d go ' marginally gunned' if I were you, I' d be getting a new gun that I KNOW will do the job where-ever a shot presents itself.