Here is a script that might help. Find and make active the view toward which you want the normals to face, select the surfaces to process. Will flip normals of surfaces if they don’t face the closes to the viewing direction. The view can also be an oblique view in the Perspective viewport, it uses the current camera-target vector to check the surface normal against.
–Mitch
UnifyNormalsView.py (1.3 KB)