Alex I am a devotee of the 358 calibre so would sugest, in keeping with tradtion, a 350Rigby. It will handle any game in Aust with the right bullet.

If that doesn't float your boat and you want something that can thump hard in close or way out then go the 416 Rigby. Trailboss is good in the 416 with cast bullets as is AR2206H.