That movement is not a Lemania but a Chinese Sea Gull derived from the Venus 175 Swiss movement.

Here are excerpts from posts I have come across.
-
-
-
Around 1957 the 1st Moscow Watch Factory started producing a copy of the Venus calibre 150, designated 3017. This was the legendary 'Strela'. A few years later Venus was planning to reduce their movement range down to a single, newly-developed item; the calibre 180. To pay for this they needed to dispose of some redundant tooling. So they went to the Soviets first, who said 'no thanks, we're happy with the Strela'. However it happened that the Chinese airforce was in need of a pilot's chronograph, and for political reasons would no longer be able to source such an item from the USSR. So Venus offered them the 175.
-
-
-

When did Seagull start to manufacture the 175 clone. Did they buy the assambly-line from Venus/Valjoux? Or copy it in some way?

I think it more likely that they simply bought the tools from Venus. I recall reading on the Russian forum about how Venus (during one of their frequent moments of financial difficulties) offered the calibre 175 tools to 1st Moscow as an upgrade for the Strela. The Soviets declined because the smaller Strela calibre 3017 suited their purposes better. Chances are that Venus took their offer to Chinese after that.

There is a parallel in the later development of the Poljot calibre 3133. Venus/Valjoux first offered the 7733 to the Soviets who turned it down. Valjoux then sold it to an Indian company. When they later offered the 7734, with technical assistance thrown into the deal, the Soviets accepted.

------WebKitFormBoundaryIoCwhCPIVXI03+rS