Do you have a pic of the knob your car has on it now?
I have a fader knob kit that my dad purchased back in the 70's when the origonal knob broke. The kit contains both the Rallye and standard dash knob bezels, one Rallye fader knob and one generic looking knob as well as some screws and nuts.
Did the standard dash use the same knob as the Rallye dash?