Since you are new to Africa you will probably want to do a PG hunt first and then leave buff and other big stuff for later. If you are a competent shot though you could jump straight in and do a buff first time too.
For just PG a 30-06 or 308 would do everything up to Eland, and a Sako 85 is a great looking rifle for that.
If you potentially have buff too go with a 375H&H,
There is only need to go bigger if elephant are on the cards. My first own rifle was a Ruger No1 in 375H&H and I dived in and did a buff with it early on. My PH buddies have either CZ550's or 70's.
If you want a truly classic and nostalgic Africa experience consider a double rifle with a detachable scope mount. Sighted in on the one barrel you could reach out for any PG or DG and with the scope off you are ele ready. Mine is a Heym 450/400. Nothing more necessary, and I opted for a red dot instead of a scope, but when mini scopes come along I'll get one.