Hey Brutus,
Not sure what pump your running, but got a big selection of new different rated springs which I use in my KB pump if any good to you. I had the opposite problem to you, too much pressure, so ended up changing springs till I got a number I was happy with.
If it were me & assuming you can easily pre oil the valve train. I momentarily restrict the oil supply to the spray bars, give the valve train a liberal dose of hose from an oil can & fire the motor.
The should be sufficient oil getting to the top of the motor, plus what you added from the can. You don't need to run the motor long to see if the oil pressure shoots up. I had to run a restrictor with my spray bar set up, in fact I used an adj regulator from work, so could easily turn to my desired flow & lock it up.
"I spent a lot of money on booze, birds and fast cars. The rest I just squandered."