I did mention the idea of a German talking to a French soldier during the 1950's. But the Blast Model French figures I've seen of that era were all vehicle crew members not facing toward the outside.

But I dug out this old kit, which features figures from the Osprey French Foreign Legion Since 1945 book, and figure C is a corporal in Algerian Winter Guard dress, figure E1 in the book. How to make it look like someone stationed in Germany, if feasible? This person would be ideal for my concept.

That figure is standing at attention, as at a formal guard post or in a unit formation, not exactly the right pose for someone involved in a conversation. Aside from that, you would need to find out which French units were in Germany at that time and modify the uniform as needed. The basic uniform on the figure should work being standard issue.