I tried to build a New Succes group too
The expensive but is the Sachs 8 speed freewheels (that and the levers). The groupset is nicely finished. I suppose it's a bit like Chorus. In later years, it used Campagnolo ergo levers and cranks (badged Sachs) with brakes that looked a lot like Modolo. I assume everything else was made by Sachs. Sachs is a German company. They bought Huret and some of the other French manufacturers in the 80's. Sachs was in turn bought by Sram, so Force is in some ways the successor to this group. It is pretty rare. The stuff is available. The mechs are particularly well finished.