I moved from M5 rods (0.8mm/rev) to TR8x8 leadscrew (8mm/rev) which meant I had to change the steps per mm.
Steps per mm should not really be a calibration per se, the correct value can be calculated by knowing various physical aspects of the machine, including the steps per revolution of the stepper motor, any microstepping the controller board uses, and the leadscrew lead. The calculation for my machine is pretty simple:
(200 steps per rev motor) x (16x microstepping) / (8mm/rev leadscrew) = 400 steps per mm.
There is also a set of calculators that can help on the Prusa site:
https://blog.prusaprinters.org/calculator_3416/
For replacing the leadscrew, as long as you know the old pitch, old steps per mm value, and new leadscrew pitch, you can work out what the new steps per mm value should be without knowing about the motor or microstepping setting. In my case, I went from 0.8mm to 8mm lead, so my steps per mm changed by a factor of 10.
If you have done an extruder calibration you may be familiar with the M92 command for setting steps per mm. The same can be done with any axis, not just the extruder, so if you do swap the leadscrew you can use the M92 command to alter the steps per mm for the Z axis without having to reflash the firmware.