I am pretty confused what you are asking. A pack can be anything from 2 to a billion. Even in wolves, pack sizes vary.
Basenji pack studies? Again, confused. Basenji packs are artificially made, dynamics and variables make them not something I'd think you can actually study. Some have 2 that can't get along and must be separated, same or opposite sex, others have a dozen that gets along with mixed. It boils down to the owner's ability, the individual dogs, the house dynamics and a billion things that come down to wait-and-see cause nothing is set in stone.
You can do whatever you want, but if the dogs decide they want to fight, you don't truly get to change that, just manage. Truthfully, it's not different in many other breeds. Opposite sexes have a better chance of getting along, but that doesn't always work! Lines that are less dog aggressive helps, but that doesn't always help. If you want more than one dog, get opposite sex and see how it goes. Want a 3rd… depends on the 2 you have for which gender and again, see how it goes.