I used 3dsmax to import the model as a single mesh, rather than multiple. Seemed to work fine. Re-exported that to look at it in wings3D...The unified is sound, the normals are right, and Max was kind enough to put a nice UV Unwrap on the model too.

EDIT - Well it I wasn't allowed to upload the .zip file. Says that 'the file doesn't have a valid extension.' Is this what the object is supposed to look like?

Friends don't let friends use booleans.