depends how good you are at electrical work.
its original servo drives will be analogue- so to use those you would require a motion controller that supports analogue servo control
ie galil, csmio a, etc these will work with mach3/4 (ive never tried mach4 yet) these systems can be fun to wire/ setup and tune for steady movement if you havnt a clue in motion control.
however- as your motors are quite low torque and voltage you could keep motors and install new step/direction drives ( www.cncdrive.com make these that would be suitable and not over expensive)
you could also go the cheapest / easiest method and change servos for stepper motors- this would work fine too.

ive had success using uccnc via a galil controller to run analogue too - however depends on your skill level once again- and how much you want to spend to have it up and running.