Am I missing something for my pedal cable?

the hole looks right, without pics of the cable its hard knowing what you are talking about.

BUT, I can tell you that my 72 duster cable has a round head that fits in the round hole of the firewall and the cable is inside of the round metal head. and two studs are on that same metal bracket and pass through the two smaller holes in the firewall and are nuted down from the engine bay side of the firewall.

also there is a little gasket that gets sandwiched between the throttle cable bracket and the firewall.