Hello again! I tried to open the file. But my max is to old to make it. Now i am trying to replicate the scene by your description, with OSL Uber Bitmap Node.
Turbosmooth set to 7 is insane overkill, but ok. I imported the OBJ and reset Smoothing Groups to a single group. I added a Slice modifier to cut away the rest of the model. TurboSmooth at 7. Displace, and loaded your EXR in the OSL Uber Bitmap node. Maybe your import settings need adjustment?