I want the "Y" axis to remain the same (pointing UP), and the "X" axis to remain the same (pointing to the RIGHT). I want the "Z" axis to be reversed, pointing AWAY from the user/viewer, instead of the normal pointing OUT from the screen to the user/viewer.

USE: I'll be using it for dimensions on a DOHC (Dual Overhead Cam) cylinder head. Imagine the head laying upside down with the combustion chambers pointing up, and the front end of the head on your left. This way the "Y" axis will be dimensions (all positive) from the top surface of the head, the "X" axis will be dimensions (all positive) from the front of the head, and the "Z" axis will be dimensions (some positive, some negative) from the outside edge of the cam journals that are closest to the user/viewer. I want to avoid using the combustion chamber surface as a reference since that is the surface most likely to change, i.e., surfacing to make head surface straight and level, or surfacing to get correct cc's, etc., etc.