My reason for suggesting the bypass spring swap was that in the last couple of years we’ve had a couple of builds that got new Melling HV or HP pumps that had lower than expected pressure.
For those builds, swapping the spring solved the issue.
AFAIK, the HV & HP pumps are supposed to come with the same spring, so if they were both supplied with the “correct” spring, there would be no change in pressure from swapping the spring.
If the spring doesn’t get the pressure to the desired point....... then a swap to a HV pump will be required.
On my 383, an original high mileage Mopar pump with the stiff spring provides about 35psi at 11-1200, and 80psi going down the track.