I think heads are the most subjective part of the Basenji standard. You can see at least 12 different styles of head out there…and probably six of them are correct to the standard, but are different people's interpretation of the perfect head.
I agree with Pat, that there is no "old style" head. If you get to look thru some old photos of the original imports, and early champions in the breed..you will see a variety of heads, some more "correct" than others. I also agree with Pat, that I like to see a short, square muzzle...but unfortunately that often goes along (IME) with a level or undershot bite. It appears to be hard to continually breed for that shorty, cute muzzle, and not run into bite issues. And I don't like to see a head that is too blocky, or cheeky, and NEVER too domey....IMO a Basenji should always be elegant. Eyes are a big issue for me. Too big and too round gives more of a terrier look.
I should point out, that when I say "I don't like to see"..that doesn't mean that I literally don't like to see it...I love Basenjis no matter what they look like...but when we are evaluating stock with a critical eye, we use this term. It is kind of like art appreciation...an art critic can LOVE a good art fair...but formal art critique is different.