as to Chinon -Kern copies; there were some (less than 100) genuine Kern optical assemblies sent to Japan to be mounted after Aarau rn out of mounts, these are in M42mounts , perfectly able to match results from the Swiss mounted ones, but VERY rare and hence quite costly. 4-500USD woul be a bargain even for an original Switar. (Source: Lothar Thewes Alpa book, - no time to look up the page number, but I have one of the japan mounted and the Swiss mounted and can confirm that the foreign mount one is quite good).
p.