From everything I have seen, or more correctly not seen, while trying to find a way to change the color of my north arrows and scale bars, it appears it is still not possible to change the type or style of north arrow using arcpy.
Also, arcpy.mapping does not allow you to add or remove graphic elements, and cloned elements can only be applied to the mxd where the original object is found. So creating a dummy map document with every kind of north arrow you might use, and cloning the one you want will not work either.
An explanation for this is found in the discussion at http://forums.arcgis.com/threads/26979-Deleting-Layout-Elements-with-arcpy.mapping:
Our objective with arcpy.mapping was NOT to recreate ArcObjects
capabilities but to simplify the scripting experience. If we gave you
the ability to add new objects (e.g., scale bar) we would need to
expose ALL of the properties associated with adding that object (aka
Arcpy.mapping is intended to work with already authored mxds and layer
files. The idea is that we use ArcMap and all of its 100's of buttons,
menus, properties dialogs to author the content and we use
arcpy.mapping to automate it.
As suggested by PolyGeo, this is something the community would have to request from ESRI in a future release.