The newer pumps put out about 1300 PSI which are used with the later Saginaw PS units. Most of the control valve type systems that Ford & GM used operated on about 900 PSI. As do Mustang II racks and Toyota units. You can get a washer kit from most speed shops to install in the pressure contol valve in the pump. From what I remember is that it took about 3 washers for the last one that I set up for a Mustang II.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine