Thanks Scott, I always appreciate your input!
Where and how the cars will be loaded will depend on the geography. That very important part of the build is yet to be determined, along with the "history" of the mine. The Three Aspens Mine which is the blue print for this mock-up had an entire different ore bin on a lower level that the ore was trolleyed to by mine cart.
I won't know for certain until I have set the distance between the upper track and lower track. That will determine how I build the mountain around the mill. Right now it's more about the depth and width of the build. Height, and where the cars will load/unload will come after/during track work.