Seems like a lot of regulator tinkerers and professional repair techs tend to get locked into thinking 135 to 140 psi for intermediate pressure settings on regulators. I have usually been a little more flexible, cranking that upward if needed to get the performance I desired.
In 1985 US Divers issued a technical bulletin (PN 7802-88) that clearly stated "The recommended acceptable intermediate pressure for diaphragm-operated, first-stage regulators is 130 to 160 psig". It specifically listed this as applying to the Conshelf XIV, as well as a number of other similar first stages enumerated in the bulletin. They did not specifically mention any double hose regulators.
I ran into that bulletin in an old manual of mine, and can email a copy of the two page document if anyone is interested.