Not to put gentleman's juice on your cupcakes, so to speak, but if you are spending the big bucks for an African safari and will have to face the time lost and added expense for following up any wounded animal, the last thing I would do would be to use anything less than a premium bullet. And, to repeat what someone earlier stated, if you get a textbook broadside shot, all is well; a quartering shot may present problems with Core Lokts.
From what I hear, both wildebeest and hartebeest are tenacious and tough to anchor. Now this is subjective but I have had little luck in the accuracy department with Barnes bullets and they usually copper plate my barrels in a short time. Conversely, I have never had any difficulty getting Nosler Partitions or Accubonds to shoot well and, though my experience with Swift bullets is neither deep nor wide, I have been satisfied with their accuracy.
So my answer to your question is that I would choose a 165 grain Nosler Partition or Accubond, or Swift 165 grain Scirocco or A-Frame, whichever shot best in my rifle and go to Africa full of confidence.
Good luck on your journey.