French thread to SPD or modern pedal?
 

I've got a 70s Gitaine that I had even then, and I'm fixing it up.
I remember having to get French thread pedals for the Sugino cranks.
I'd like to put clipless on. Can I? Do they come French? Is there a solution?

Rethread the pedal arms. Haven't done it myself but supposed to be an easy job. Get a good LBS to do it as buying the LH thread tap would be too expensive for a single use.

Fr thread diameter is ~0.55", standard thread diameter is ~0.563 nominal for both
sizes. Thread pitch is identical for all practical purposes for the length of a pedal
thread. It is a trivial job to run the taps through if a shop has them available.