Norma are making 470NE ammo with the great 500gr Woodleigh soft and solids.
In the area you are hunting you might get a chance at Hyena off a bait under moon or flash light and there are some Wart hogs on the flood plains. Both these animals would be hard without a scope fitted rifle.
For the Cape buffalo a Merkel 470NE would be great. This rifle worked well for me just over the Sengwe river from where you are going.
Regards,
ozhunter