I found a neat animation or simulation of this model on YouTube.
I did a concept layout in Sketchup using the gear pitch diameters, to see if the over-all model size would be ok.
I decided this was too big of a model, so I scaled it down some......
I am going to use the new version of the GearDXF program on my computer to make the gears.
The standard scaling factor was .083333 on the spur gears, so I used that ratio to scale the rack gear and it seemed to work, by checking the fit of the rack teeth to the gear teeth.