Some good advice has already been given, but can I ask why you feel you need to fit a scope to the .470 to shoot it properly?

There's plenty of people who manage to shoot the large calibres (bolts & doubles) with open sights and whilst you might battle with the sights you currently have fitted to your .470, you could probably change them to a different, more user friendly set up.

As an example, the red fibre optic foresights make a world of difference. (See pic below & sorry it's not a better pic)

As to your original question, I think you'll find Zim permits the calibre you mention and I get an idea some of the French speaking African countries also do. Cameroon rings a bell with me, but I'm not 100% sure.