My concern with this situation is that the issues these two are having is something that should have come about during a trial period. Were they introduced on neutral ground? Were they in the same space for HOURS before you decided to adopt the lab?
I think that maybe the decision to adopt the lab wasn't thought through as completely as it could have been and it's unfair that as a result Lady will have to go through another major life change. If you're going to add another animal to the household, and this is as big a life change for Lady as it is for you, I think you owed it to her to make sure this other dog could be her friend and integrate into the pack. Maybe your assumption was that all dogs do (should?) get along, no questions asked. Not all humans get along, that is for sure, so why do we expect this of dogs?
I agree with other comments that in no way should Lady be labeled aggresive for how she interacts with Raven.
Also Lady's growling when you pick up her possibly suggests that she sees herself as leader of the pack. Basenjis need a very strong alpha human to keep things in order. If she sees herself as ruler of the household she's dealing with an intruder who became part of the family without any of her input and certainly not her approval.