The M39/M42 Adapter-ring arrived and fits now perfectly on the Z - M42 adapter with the Scitex 67mm f/4.9, the lens with the shortest flang distance.
A construction for a sunhood was easy, the 49mm ring fits just over the top of the lens, combined with a step up ring to 52mm matching the many sun hoods Nikon made for the 52mm filter size.