That is the transformer I have looked into already wouldn’t the wye secondary require the 4th wire (neutral) ? It’s not required on any of the loads. There all 3 wire loads. Would delta delta step up be better ? Maybe cheaper although at $1600 for refurbished I’m not complaining to much. It’s doubful I would ever need the 277v for lighting loads.Transformer suppliers probably have stock of 240D to 480Y 277.
Regular electrical supply houses may have lesser chance of stocking them as they wouldn't be as high in demand as 480 delta to 208/120 wye.