Engine goes right to full throttle/advance

I did my best, Dart66. 68 Sedan is right, a bad power valve will provide excess fuel, but I still don't think it would make it rev out of control.

If you back the idle speed screw all the way out, it still revs out of control, right?

This problem is driving me nuts. I wish you were closer so I could take a look myself.

Is something interfering with the throttle shaft, like the intake manifold or a spacer? Maybe even a vacuum line binding it up?