Hello,
In our Lyon mint master list : https://en.numista.com/catalogue/mint.php?id=75 there is a gap before Jean-Claude Gabet, as quoted in https://fr.numista.com/forum/topic171405.html#p1311677 by Hervé (Quoting Gadoury):
"In the Gadoury (white) “French royal coins” ... for the Lyon workshop from 1752 to 1784, workshop directors Charles Millanois and then Jean Millanois used a bird as a mark of distinction (page 14 of the 2012 edition).
During this same period, there were several engravers who all used the same mark, which was a bird's head on the left, found on your coin after the date:
1743 to 1759: Clair III Jacquemin
1759 to 1760: Clair IV Jacquemin
1760 to 1794: Jean Humbert Bernavon
Can we put these names in the Lyon Mint Master list?
This is an idea of their mark extracted from a picture: 
Many thanks in advance.
Hubert