@s_y I know what you mean about the restrictions; but on the subject of simple black line work, it can be very effective on its own, and indeed there is classic simplicity about it also, and is often used for tribal patterns and text designs, with quotes, ref.s from the Bible, etc.
So I was wondering if in fact "as is" was what you were aiming at...
Of course, shading and color does transform the design, naturally.