For safety, mechanically disconnect the motor from the printing press.
Some printing equipment can pretty much self destruct if run backwards.
AC/DC motors have brushes. Speed is controlled by voltage and physical load.
Generally two wiring schemes are used, parallel, and series.
Series wired, have good starting torque, and poor speed control,
so should not be started without a physical load.
Common series examples; car starters, vacuum cleaners, hand power tools.
Parallel wired, have better speed control, and lower starting torque.
Investigate the motor wiring. An ohm meter reading of each pair of wires will help.
Many AC/DC motors have access to the brushes on the outside of the motor.
If this is the case, carefully remove one of the brushes (paying attention to how it is installed).
Then re-test the wiring, to identify which pair power the armature through the brushes.
The press manufacture may be able to help, if they originally installed the motor.
If all else fails, plan on parallel wiring for the motor.
Many armatures have very low resistance, so would draw excessive power on starting.
The inductor may have been wired in series with the armature to reduce the starting surge.
Some printing equipment starts at a lower speed, then comes up to running speed.
The variac may have had an automatic power reduction mechanism when powered off,
so when started, it would start slower (lighter load), then come up to speed.
If this is a small press, the operator may just set the speed and have a start/run switch.
The motor wiring also determines motor turning direction.
Verify motor direction, before mechanically reconnecting.
Once connected, turnover the press by hand first, to see nothing is binding before power is applied.