Older cruisers and large destroyers could receive AA conversions

Would older French cruisers receive C-class-style anti-aircraft conversions?

Possibly; the oldest available cruisers are candidates, while some contre-torpilleurs might gain British 4.5-inch dual-purpose guns instead.

The oldest available French cruisers are possible candidates for anti-aircraft conversion. Some older contre-torpilleurs could also receive different gun mounts. Replacing their 5.5-inch weapons with 4.5-inch guns would be justified by the improved anti-aircraft capability.