David Cross in England e-mailed me in March 2006 that he has converted some Pentacon Six lenses for a Pentax 6×7.  Here is some of what he says:
    “So far I have adapted the Pentacon 300/4, the CZJ Sonnar 300/4 (which slips nicely into an outer bayonet extension tube with minimal machining) and a zebra finish Sonnar 180/2.8; this particular lens had a rear element assembly/baffle in two parts so required no machining off the length of the baffle-I have another sample of this lens which would require machining here.  These adaptations have no stop-down linkage - not something I feel is too much of a problem in use.
    “Feel free to pass on any enquiries on this subject to me.”
http://www.pentaconsix.com/p6lenstop67.htm 
                
                
                                
                    modern art = i could do that + yes, but you didn't