You can change out throttle shaft O-rings yourself without needing a recalibration. Especially easy on older pumps, like those found in a 6.2, because no adjustable guide stud. Remove kick down stuff from the throttle shaft, pull the cap, remove the guide stud, rotate mini/max block out of the way, slide the shaft out, replace O-rings. Good time to look for a groove wearing into the stud from rubbing the metering valve retaining wire. If the groove gets too deep you will get a sticky spot in the throttle travel. A little emery cloth cleans this right up. Other than main shaft seals, you can change out most or all the other seals without messing up the calibration. You will know when a main shaft seal is gone because the weep hole on the bottom of the pump close to where it mounts to the timing cover will be leaking. Leaks from the housing will rob you of performance because the fuel advance system works by balancing housing pump pressure against spring tension. Leaks allow housing pump pressure to drop, so your timing will be off vs whatever it was calibrated for. In the most extreme cases the motor will "hunt" at idle, because the housing pressure is so far off the advance servo spring will start to bounce, and then your swinging back and forth from retard to advance.
All the seals in the IP have an SLC (shelf life code) assigned against their respective NSN's. The NSN for IP should carry the SLC assigned to its shortest SLC down-part. This is based on vendor data provided during the provisioning and initial cataloging of the repairable material. Curious what SLC the various stock-listed IP's have assigned....