Priobe,
I'm using the Precision high volume
oil pump in my 428. When I first put the motor together, I installed the spring spacer to give me the higher
oil pressure. For my motor, that was a big mistake. When the
oil was cold, I'd peg the meter at at well over 100 PSI with the RPMs above 3000 or so. Even once the oil got hot, I was looking at pressures of about 90 PSI. I tried running thinner 5W-30 oil and that made only a marginal difference. I finally pulled the pan and removed the spring spacer. With warm oil I now have about 65 PSI above 3000 RPMs and about 35 at idle.
I wouldn't use the spring spacer unless you have exceptionally large bearing clearances.
Chris