Finally I decided to get the same effect using mono printing. I made some more complete sketches which I worked from to make mono prints. (I inked a piece of glass and then redrew the image on a piece of paper placed on the ink. The image is formed by the pressure onto the ink)
The mono prints were looser than the sketches and at last I got an effect that I was happy with. I created a document and fitted the images around the text.
I think I could refine my technique a bit more, maybe make the images a bit easier to read, but I felt satisfied for now.