Ho-hum. Well I'm not quite sure what your information means, but I assume that you have a stepper-servo drive with a 4000 line encoder, the stepper being 200 steps/rev. If I understand these devices correctly, the stepper is irrelevant, it just needs 4000 input pulses to get one rev of the motor. The goal is to set a parameter in M3 which is steps/unit, i.e. steps/inch. No real need to calibrate if your machine data is correct (though 18 tpi is an odd leadscrew pitch!). (Getting 4000 steps out of a 200 step/rev motor just needs "microstepping" by a factor of 20 which is handled by the driver.)

You need 18 turns of the LS to get 1 inch of movement. This corresponds to 22/19 revs of the motor (why those ratios? Seem rather odd). So steps per inch is 18 x (22/19) x 4000 = 83,368.421052631578947368421052632 STEPS though you could ignore everything after the first decimal place.

Could you actually have a metric leadscrew of 0.7mm pitch? Even then that's odd as feedscrews are usually chosen so one rev is a convenient feed in native units.

I run my lathe in metric, it has a 5mm pitch cross-feed screw but an 8 tpi leadscrew. Steps/mm for both were calculated as above and are exact as far as I can measure