I just built a chassis with a 1000 watt 90Vdc PS and 3 Viper 200's mounted on their edge. I will post a picture.
I get the toroids made here in Canada by SumR in Toronto. Costs more than china, but exellent service and quality. I get a 12V 1 amp secondary winding to power the control board in the same transformer.
Those motors should be no problem.
No one ever puts a PS capable of driving all 3 motors continuosly at peak current, unless you know the machine will be at 100% load all the time.
20-30 amps should be fine.
Manufacturer of CNC routers and Viper Servo Drives
www.LarkenCNC.com and www.Viperservo.com