Here's something to think about:
Different pumps put out different pressures based on the application; The pump, which had a return line, i used for the 350 was putting out close to 7lbs. The service manual for my 83 called for 5 to 7.5 lbs if the pump has a return line and 7.5 to 9 lbs if no return line!
Then when i switched to the 305 which came out of a 78 malibu, the pumps for 78 malibus didn't have a return line (rochester 2G) was it putting out 9lbs in this case? i'm pretty sure it wasn't.