I looked at the cupola yesterday with a view to replacing it. I mentioned above that it can rotate on the real vehicle, but as I found yesterday it's not so straight forward. Most of the pictures you see of Chief are with the GPMG trained fwd, few show any other direction. It turns out the lower periscopes with the washer/wiper units are fixed & only the internal part - with hatch, gun mount & TC's upper periscope - are traverse-able. You'll see on the model that there is a moulded seam between the two. If you fit Haya's 3D update kit cupola cover as is, you loose sight of this, though it too should have an inner & outer.
The Haya 3D kit - yes thought it was fairly expensive, but on reflection, given the number of pieces you get, it's comparable or better than Shapeways costs that I've paid.
Mal