Transformer sizing

Hi All,

I need some help in sizing a power supply for a Bridgeport series
1/EMC conversion. I will be driving each axis with 140V SEM PMDC
servo motor of which the stall current is 26A. The drive powering
these motors are capable of supplying 100V @ 20A. I will drive a 5mm
pitch ball screw thourgh 2:1 reduction ratio. What VA transformer
should I purchase? Am I ever likley to use 100V @ 20A? Should the
reduction ratio be bigger ie 3:1 or 4:1?

Many Thanks
Craig