If you have Kadrons, then 1.5# fuel pressure.
If you have Weber/Dellorto/Solex, then 3# pressure.
Back out of your fuel system "upgrades" one step at a time: Kinked hose/line somewhere? It sounds like a clogged fuel filter so you're not getting full flow - can you by-pass the filter with a short piece of hose one at a time to see if that helps? Do that for the fuel pressure regulator, too. If you have a single filter before the pump, that's all you'll need - one after the pump isn't necessary. I doubt that it's the pump, as it had been working OK before the changes, so I would suspect one of the upgrades. One of the upgrades was that 10' of hose, which is cheap. Get another 10', make sure it has no obstructions and re-install. That's all I've got.
If you can feel the scratchiness in the steering wheel, then I would suspect the bearing at the top of the column, right under the steering wheel. What is in there depends on the year of the VW donor column. 54 - 67, 68 - 70 or 71 - 79 all have different top bearings and different spacers. Long way to ship, but this might show you different ones to get something closer: