[Walt Fricke]

"System pressure (fuel pump on, engine off) - 65psi (4.5 bar) BOTTOM OF SPEC, BUT STILL IN
Cold control pressure - ~25psi (~1.8 bar) SEEMS RIGHT DEPENDING ON AIR TEMP
Warm control pressure - 50psi (3.4 bar) SEEMS RIGHT

When I started the engine, it started at 1.8-2.0 bar and just slowly rose from there to 3.4 bar over the course of 30 - 60 seconds. Then just sat right at 3.4 bars from then on."

This is just what the WUR is supposed to do - low control pressure for rich, easy cold starting. Then leaning it out (rising CP) until the heating coil in the WUR has caused the bimetalic spring to completely disengage from its job of pushing down on the pressure springs.

I'd be inclined to look elsewhere for your issues. What are your AFRs and CO%s?

And why are you pumping the gas? There is no acceleration pump feature on these cars - pumping doesn't really do any good, and may help flood it. Yes, if it coughs and sort of catches, a bit more throttle probably helps. But that indicates it is out of tune - as you know.