Finally got hold of some late 70s FeCr cassettes with blank labels/cards, super cheap. FeCr tape has always been a thing for me, since my childhood. The compilation is my own -
Vintage Audio Cassette SONY FeCr 60 * Rare From France 1978 * . | eBay
Pack of 10 Sony FeCr 90 minute Cassettes 1978 | Reverb France
SONY FECR 90 Cassette audio k7 tape vierge neuve sous blister sealed EUR 19,90 - PicClick FR
The Type III Ferrichrome / Ferro-chrome Audio Cassette | Tape Tardis