If you can discern shadows like in the folds of the dress, it’s going to produce an incorrect result. Height maps inherently looks weird. They should look more like an X-ray than a marble sculpture.
If you wanted to do this with lighting you would basically need to simulate a light from head on that gets dimmer the further away the object is. Some sort of linear drop-off. The material should have no reflectance (completely matte) and ignore effects like ambient occlusion.
Note: I’m not Blender-proficient, so that’s a more general, non-specific description of how to set it up.