Most machines are built to run 208. In Utah, buck transformers are common as UP&L runs high on voltage. Look at your transformer, measure your voltage and choose the tap closest to your measured voltage. Many shops run undersize wire as Full Load Amps is seldom reached. 6 gauge will run 68 amps just fine, which is a very heavy cut. Do your servo motors have permanent magnets or are they the old three phase wound motors. Fanuc, Siemens, Yaskawa motors are modern in design. You most likely are talking about a Haas as these are affordable and use modern motors. Okuma mills have a good but complex tool changer, requiring an amplifier, encoder feed back, and motor on track to move the carriage. Haas will just have a pneumatic system with a homing circuit, tool forward and back sensors. About 90% fewer parts and dirt cheap to repair.
Sounds like your running CAT 50 tapers, is that right?