French period saddles for your bike are not hard to find!
You can keep it period correct and still mostly French if you replace it with an Ideale brand 2001 or 2002 model saddles (They can be found NOS at eBay for as low as $75 bucks for the most basic versions). You can also get Ideale leather "suspension" type saddles that are similar to Brooks leather saddles in design with some sprung versions too, but they are generally much more expensive than the 2000 series model with the padded plastic base and leather covers.

Chombi