^^ That's not the correct knob. You can't get the right ones new, gotta go vintage.
Take a look at the "8" see how the lobes are about the same size? On a vintage know, the lower lobe of the 8 is much larger. They call them Snowman 8 knobs.
I have a blackface showman head that had two wrong knobs when I got it. Once you see them, they really bug.