Hi all,
I did some research about verdaccio color. Here what I discovered.

In 1200 painting was not so diffuse in Florence and governor of city called some Greek painters to decorate some churches (see Vasari book). There started to work Cimabue that learned to use verdaccio as an underpanting of flesh color.

Before apply verdaccio he did a line drawing and traced some dark area with terra verte (earth green) then on top of it applied the verdaccio.

Cimabue taught the process to Giotto. Giotto taught the process to Taddeo Gaddi that was his pupil for 24 years. Taddeo taught it to his son Agnolo. Agnolo taught it to Cennino Cennini that reported the process in his Craftsman's Handbook.
http://www.noteaccess.com/Texts/Cennini/

No green pigment was used. Only black, yellow ochre, white and red. White in the english text is called white lime but actual Italian name was "Bianco San Giovanni" literally can be translated in "White Saint John" but I do not think it exists any more. Yellow Ochre was available at that time in two versions: dark and light. Cennini wrote to prefer dark if possible. The red was Cinabrese. So no green was present in the mixture.

Also the recipes provided by Wikipedia seems wrong because it does not cite the red.

So I think your recipes is pretty good because you cited yellow ochre and blank. White was used for light area. You missed red probably used to neutralize the green color and make it more gray.

I wrote an article on this here.
http://www.drawandpaint.net/verdaccio-underpainting/

Let me know what do you think about my research.
Thank you