Actually this is a good point. 14 inches was the target and I took the figure from the original layout document. In review, I wonder if the end number did not wind up a setback of only about 10 inches.
The firewall that is there is quite a ways back from the original- it is basically missing all of the firewall from the cowl trim below the windshield forward. The cowl trim was modified (filled in the grille since the heater vent is gone). If you look at the image on this link
http://www.rscamaro.com/images/rsCamaro/firewall.jpg you can see where the new firewall starts right at the front of the doors. This is about 7" being the original location. The original setup had quite a bit of clearance with the motor; this setup has some clearance, but to get the motor loose of the bell housing, there is a plate on either side of the trans tunnel that is removable to give access to the bolts.
If you sat in the car with a seat and the firewall only, you could really tell that the thing was shifted back. The foot boxes help and the dash extends back a bit more than the stock one as well; I believe this somewhat helps to "hide" the modification.