Did you drill your fitting to 5/32" when you added your hydroboost?Enough to cause enough flow restriction to burn up a pump?
PSC recommended I drill mine when I added my hydroboost to add more flow.
More information here, Modifying your Power Steering Pump - GM Truck Central
Also think about switching over to SWEPCO 715 Power Steering Fluid, it solved a few of my issues on my U4 car and I run it in everything now.