How do I go about turning up the IP on my 1989 6.2 n/a?

you have two options:

Remove the top cover from the pump, unscrew the guide stud out the back and rotate the throttle lever to remove the governor assembly. Roll the engine over by the alternator pully while you watch through the hole in the cam ring for the 5/32" allen head screw on the leaf spring to come up.
When you reassemble it, make sure you put the red spring back inside the governor assembly (if yours has an adjustable guide stud, '89 should). put the governor thrust spring back in the groove on the guide block before you install the guide stud, then using a flat head screw driver, push it into the boss on the inside wall of the governor housing. And carefully replace the top cover, ensuring the ESO is on the front side of the governor arm.

Or you can remove the oil filler tube, and roll the engine over till the locating pin on the drive shaft of the pump is in the 10' Oclock position. Remove the two 1/4" bolts on the inspection plate on the side of the pump and turn the leaf spring from there.

I'd suggest an 1/8th turn or less on a N/A engine.

thank you Texas diesel guy. I will attempt this weekend. (if I get time)