Most large cats work well with rays but these guys seem pretty nippy I would not try it myself. Go with a Niger or a Irwini or even one of the shovel nose cats (tigrinus,Juruense)
I know their peaceful but can get past the horse shape head and face of a Niger both cats got huge spikes I don't want my Ray to get scratches. Tigrinus sure... But I need a big one and their not cheap at size.