to smooth Power Steering

Separate the high pressure hose from the pressure valve assembly. The pump and reservoir will drain empty and that high pressure hose might drool a bit and develop a small air pocket. Not really enough to be concerned with. Screw the valve out of the back of the pump, mod it, put it back with a new O ring.
I don't have a clue about washer thickness other than what I read. I suppose its trial and error to meet individual taste. Anyway... once back together, fill to half the reservoir neck, run it and steer stop to stop. Recheck fluid level after any foam clears.