I have a set of 13" hi-hats.
To add to your list UFIP and Zanchi. They were making cymbals back into the late 40's at least. UFIP is a company that dates it's beginnings to 1847 but that was as Bell makers. Who knows exactly when they started making cymbals. They just might not have called them UFIP.
It is theoretically possible, that they were always the producers of Ajaha and the change to the ink stamped ones from the signed ones corresponded to the change to rotocasting. At any rate , I would put Ajaha on the list . They have been around since the 20's and the very best 20" ride I have ever owned is a rotocast Ajaha and that includes some pretty lofty competitors( K.Zildjian,A.Zildjian,Zilco,Zanchi,Super Zyn,Paiste Formula 602,Sabian,Diril and another Ajaha).