Ando--
Following Jerry's update above, when I swapped from the "modern" (eg. more cost effective, cheap) version with the ball bearing, spring and bolt/washer/nut to the original integrated cone/pin assembly, it got a few more lbs PSI. Most of it I think was due to a build-up of gunk on the pressure relief mating surface. I used one of Don's tools, but a hardwood dowel and some creative hammering/tapping will clean it up as well.
Also, I got a touch more oil pressure & stability using Indigo's external oil filter. Indigo's solution blocks the original oil regulator port and has an external oil pressure regulator built into the filter holder which make for much more convenient adjustment.
IMO, either is an improvement over the "modern" version.