Normals/texturing issue

Howdy y'all, I'm running into an issue with normals or textures or both, and I'm not entirely sure how to solve it. The issue I'm seeing is that after I build and texture my model, Three.js will only show the bottom of the map with the texture, or the top of the map black, neither of which is correct, and I'm not sure what I'm doing wrong.

My work flow is like this:

1. Sculpt and texture the map from a plane in Mudbox.
2. Export as obj file.
3. Mudbox does not export the .mtl file with .obj files, so I import the mesh into blender then immediately export it.
4. Convert the mesh to js using the Convert_obj.py script provided with Three.js.

In my scene, I'm using the JSONLoader to import the model. I also have a reflective water plane that is generated in the scene (No external geometry). When I load my scene, the water shows up, and I can see a reflection of my model, with the texture on the bottom side, but I cannot see the model itself. If I flip the normals in blender, or set my material to THREE.BackSide, I see my model, but it's completely black, with some color around the edges, like it's being lit from below (Which it isn't)

I have gone through 4 different versions of this model, and all of the other ones behaved properly, but not this one, and I have no idea what's different. Anyone have any clue what I could be doing wrong here?