I did a bit of searching and really all I can find is that it uses 100 oz in steppers and for the spindle a DC motor.
I dont know what the drives are but it may be possible to wire them to a breakout board and work from Mach via the parallel port, if not then you would need new drives. Gecko does the G540 which I think would probably suit your motors (would need to find specs) and has a built in breakout board.
Spindle would possibly be a bit more involved, it depends what its drive needs as a signal but it may be possible to control it via the G540 as well.
Down side is the G540 has 4 axis and you only need two so it would be two drives sitting doing nothing, in itself not a problem but you are paying for them even though you are not using them. Suppose they would always be spares in case something went wrong although thats not likely as Gecko steppers tend to be very reliable.
Having said that it may work out just as cheap getting the G540 rather than a breakout board and two drives and then a spindle control card.
So worst case you are likely looking at $300 (obviously dependant on stepper and spindle specs) for the G540 and a bit of time wiring, best case is a breakout board and spindle board at probably around $100 or so.
Hood