Not much you can do about iron, since you probably need iron to capture it from Shaka. It's seriously sucky if you have to defend from a full-on human invasion pre-Rifling, since xbows are huge there. Maybe muskets are ok, though, I just haven't used them much ever.

I think a Rifling beeline would be good. Given the tech pace, you should have a huge Cavalry window against African AI.