I confirm : at least for the last 3 sessions, the movement used at the Paris JLC Master Class has been the Calibre 875 from the Reverso Grande Date, which has indeed a 8 days power reserve. It is the same movement as the one used for the watchmaking game on the JLC web site.
Not to be confused which the Reverso Grande Reserve aka Reverso 8 days which is now discontinued. Movement was ref. 874.