Jan,
I am going to have to disagree with the idea that these none serial numbered guns are not a normal variation. There are numerous examples here in the US that are finely finish, complete with correct grips. These are highly finished pistols produced in the factory. If these guns were taken from the factory with out German knowledge then they were completed guns. These guns are very early German controlled production guns. They have all the early features and are highly polished and nicely blued. These guns are not your lunch box specials. Mark’s gun does appear to have a none standard takedown lever, that could have been made at any time. His is not the first pistol that I have seen that has some none factory replacement parts. There are enough of these pistols out there that I would consider them a known variation and a must for any serious Cz-27 collector.
Respectfully,
Robert