Prusa Y-Axis Torsion Motor Mount

I recently replaced the 5mm timing cables for the X and Y axis on my Reprap Prusa with SynchroMesh Cable.
(https://sdp-si.com/eStore/PartDetail.asp?Opener=Group&PartID=84751&GroupID=768)

I used the pulleys (http://www.thingiverse.com/thing:15923) shared by Granz initially with a 15 tooth pulley.

Looking at the pulley in situ it was very obvious to me that it is very much more compact than your average 5mm belt pulley.

A plan was hatched. I had planned on producing a torsion box fo