I would say B - and to make sure that you generate your level 7 normal map off the level 6 base mesh so that you're not trying to fake geometry with the normal map that you've already achieved properly by displacement. The normal map should be for the very fine details at the end.
Failing all of this, if RAM consumption isn't a huge issue and it's a still object, just bring in the level 7 model, convert to proxy and be done with it! Just another option that saves relying on these maps being entirely correct along with their settings.
