Factory fuel pump
The pump has nothing to do with reg. It should dead head at close to70 psi without factory reg installed. Not sure about extra intake part of pump, thats different from stock design I am used to. We use a different filter/reg on our systems, its a jeep part. I believe the vette filt/rg runs closer to 65 # and if I remember the later Hemi uses 58# and the first few years used 48#. What year was your donor?
I do have the part number but I believe that's a 05 ram fuel pump assembly.
I have been running a walbro 255lph pump and with the corvette/filter reg, I constantly get 50psi on prime with this pump, but 58psi once the car starts. I thought my fuel pump might have been on the way out, so I replaced with another brand new walbro 255lph and it also primes to 50psi and has the exact same running conditions. Hard starting, takes a few goes to get the engine to fire up, when it does fire up it coughs and splutters stalls, after a few goes it does run and idle fine, it occassionally has a slight rough patch but then might sort itself out. Responds ok to light throttle application, but a decent hit with the throttle and it bogs right down and stalls. I have also replaced the filter/reg with another wix one. The injectors are the stock 5.7's that came with the engine. Had them cleaned, re-kitted and flow tested. Yet still the car runs like this.
Brand new battery, brand new pump, brand new filter/reg, new gas, rebuilt injectors, checked pcv valve, cleaned throttle body. It's starting to get beyond me and I don't know what to look for. No engine codes are up other than:
P0480 - Fan 1 Circuit Control
U0155 - Lost Communication with Instrument Panel Cluster (IPC) Control Module
These I believe would show on any car though as it can't see the factory dash or the factory fan setup. These have always been highlighted on the car and it's running the hotwire wiring harness.
I have live data but I can't make much sense of it.