The N27 brain is a standardized template that is going to be different in shape from other standardized templates, such as the the icbm452 template, the mni152 template, or the Talairach-Tourneaux brain. Although all of these templates are often referred to generically as "Talairach", there really is only one true Talairach. The "Where Am I?" feature in AFNI uses the Talairach coordinate system to identify locations in the brain. As such, it will only be accurate if the brain has been warped to the TT brain.
Peggy