Ben,
Sorry I need to answer your PM.
We have fitted a couple of Cusco cages that fit very nice , the cage in my Trackday car as per the below link, has door bars fitted and the stock door cards still fit nicely, the roll cage goes down the back of the stock dash , it does require some work to make it fit nicely but it looks lovely.
http://www.350z-uk.com/topic/91461-abbey-motorsport-350ztrack-project/
I can supply.