No idea, sometimes with mixes it's so hard to tell what the parentage is. I do think that your dog's head is a bit more refined than many of the pit mixes i've seen.
Oh yeah, he looks way more like a b-mix to me than a lot of the pups listed as basenjis on Petfinder. And they mention he's not a barker. What a cutie! Someone go get this guy! :D