You can probabally put the encoders on the motors, or B.S. if it is easier, the Excello's and some B.P.s used encoders on the motors.
The drives you have are velocity style, the modern replacement is Current or Torque mode amps, with these you could do away with the tach.
Do you really need a high end control if it is a simple repetitive program?
I have achieved similar to this with a Galil and a 2 line display/keypad for operator interface, just to enter data into a data base for e.g.
But I guess you have everything now?