Pete, if you get a .50 with a 1/48" twist, you can shoot conicals like the 370-grain Maxi Ball, the Hornady Great Plains bullets or Buffalo Bullets in it for game the size of Kudu and Wildebeest. A charge of between 100 to 120 grains of FFg or equivalent (Pyrodex RS, T7 FFg, etc.) would give you plenty of killing power out to 100 yards. If you get a rifle with a 1/4X28" or 5/16X32" nipple thread size, contact
October Country and buy a MAG-SPARK nipple for it. This allows you to use No. 209 shotgun primers instead of No. 11 caps, thus giving you all the advantages of an inline like the Knight, as far as ignition goes. I have two sidelocks thith "semi-patent" breeches, in which the flash comes out directly in the center of the breechblock, permitting me to use pelleted propellant, if I so desired. But I use loose powder, and put my powder & ball in one of the plastic "cartridges" available.
If I were going to hunt in Africa with a ML, I'd try to get a Pedersoli Kodiak in .58 caliber, and use the Lyman 57730 mini-ball in it with 120 grains of Swiss FFg powder. This bullet weighs 570 grains, and from my .58 cal. flintlock Hawken with 36" barrel, it has a MV of 1200 FPS using 120 grains of FFg powder. I believe this bullet would kill anything in Africa.
For the smaller species of plains game, a .570 round ball would work quite well at speeds of 1500 to 1600 FPS, if you can find a .58.