Hurco liked those Servomate amps - and with good reason.
They used analog +10v, 0v, -10v type DC brush servo amps which are not readily converted to step/direction (not that you would really want to degrade the system with that. (With the tach feedback that analog control is very tight)
You will crawl using geckos as they are not built to run at 90V all day (not to mention reversing loads).
Here is a link to the manual.
(Cleveland Motion Controls) Servomate SM1