Horseman 6x9 focusing cams w/non-Horseman lenses?

Does anyone know if focusing cams for the Horseman 6x9 field cameras (980, 985, VH, VH-R, ER, etc.) are usable with other lens of the same focal length? That is, can the focusing cam for the 90mm Super Horseman lens be used to focus a 90mm Schneider lens? Wouldn't the extension required for a given focus distance be the same for both lenses, and if so wouldn't this make the cams usable for other 90mm lenses? Likewise for 75mm, 65 and 150m cams? Does anyone know anything about this?