The grayscale images had to be converted to a mezzotint to match the mezzotint prints of Catherine the Great and Queen Victoria. The client provided a copy of the mezzotint prints to help figure out what lines per inch mezzotint to use.
The line conversion was made using the Andromeda Screens Filter. Just selected the filter from the filters menu, picked 55 lpi mezzotint, clicked OK and it was done

Mezzotint detail