How to select the correct DC servo motor
Before looking at motors, you need to define a few parameters, apart from the load mass and leadscrew pitch. First, what is the motion profile? I assume the device won't be in constant motion. Is there a defined sequence of movements? What distance and elapsed time for each move? What elapsed time between moves?

Next, the load. Is it affected by gravity? Are there other external forces acting on the load? What about friction? You should also know the diameter and material of the leadscrew (for inertia calculation).

With all of that, you can proceed to calculate peak torque, RMS torque, and speed required at the drive end of the lead screw. That will indicate what sort of motor you need.

Then you need to consider the ratio of the reflected load inertia to the motor's rotor inertia. A high ratio will necessitate de-tuning the position loop in order to get stability. Ideally, the ratio is 1:1 (hard to achieve), but under 3:1 is generally very good. Under 6:1 is generally acceptable. If the coupling is "stiff", 10:1 can be OK.

If the inertia ratio needs reduction, first look at a bigger motor. Otherwise, a gearbox may be required. Reflected inertia reduces as the square of the gear ratio. But speed requirements increase.