That rifle would handle anything in North American for take down. After all a .58 caliber is a very large bore rifle. For instance a .50 caliber roundball weights 177 grains. A .58 caliber is 282 grainsI think it is. When you push that ball into the vitals of an animal it has already made over a 1/2 inch hole going in. If it expands at all, it only gets worse for what ever you shot.

The Zouave was a military rifle. Some of them actually had a bore of .577 instead of .580. They shot minnie ball out of them. The load was normally 60-70 grains of 2f black powder and a minnie. The object was not pin point accuracy but instead just push a hole through the target. The size and weight of the minnie would normally do the rest.

They will shoot a roundball. I would get some .570 ball and .015 patch. Start with 70 grains of Pyrodex RS or Black Powder in 2f and then seat that patched ball on it. Be advised, many of them rifles were made to shoot high... In the civil war the target sight at close range (from what I have read) was the belt buckle. This would put the projectile into the chest area of a man. At long ranges they could them aim dead on and compensate for the drop of the projectile without thinking too much. So if your rifle is shooting high, there might be good reason. Although I tend to think the new production models would have been more sight true.

Semisane can tell you a lot more about the shooting ability of the rifle. Since he has been making modifications to his and maybe doing some load testing as he is a powder junkie and likes to shoot I believe. I never had the pleasure to shoot a Zouave, but did for a long time shoot a Springfield Rifle. My friend who got me into shooting black powder owned an original 1861 Springfield Rifle. We could hit a gallon milk jug at 100 yards with a patched ball and 70 grains almost every time with that rifle. It was a lot of fun to shoot.