Bibala sits on the inland route between Namibe and Lubango. Road conditions can change, but this is one of the more logical overland corridors in southern Angola because it links the coast, the railway, and the highland road system.
The town is also served by the Mocamedes railway. Do not assume passenger services will be useful for a tight itinerary without checking locally; in Angola, the timetable on paper and the reality on the day can be two different things.