Just because a fish in your stock has flared, long fins doesn't make the other fish turn into nippers. I've seen angel fish in tanks with Arowana with no problems. In this scenario you just need to make sure whatever you stock with the angel is not known to nip at fins. In this case I don't believe african cichlids are known for nipping, but again, I don't have much experience with them.
Don't forget Angel fish are also a cichlid and can be semi aggressive themselfs.
Don't forget Angel fish are also a cichlid and can be semi aggressive themselfs.