430 mm along the Y axis, around 80 mm along the Z axis - this is the scale.

I use Artcam 2018 for roughing, most of models are designed in Zbrush, sometime in 3dsMax.
It took 48 hours to carve it. ) Also, the design has to be of a high quality to achieve such results, I have used this one.
https://3dwave.org/product/indian-skull-2/

Let me know if you will have more questions, I am looking forward to share our experience :)