Hi
Every pump i'v seen has had the pully press fit.You need a special tool to remove and replace the pully,or you risk damage to the pump.
The tool kit i have for this job is made by KD tools.It has a clamp for the pully and several different treaded bolts to thread into the pump shaft.The tool pushes the shaft out of the pully,and pulls it back into the pully.Just have to make sure you set it to the right depth for alignment of belts.
You could probly build some tools if you don't have anywhere to get the tool.
Thomas
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews