I am not sure what your container fill time data will tell you. You have already observed that the replacement nozzle is not flowing as much as the other 5. No matter what your data shows there will not be much flow at idle when the pump is only capable of producing 2 psi with hot oil. Remember that pressure is the result of resistance to flow.
My best guess is that there is some type of blockage in that pipe. It could be excess solder from the repair joint or it could be a piece of very reluctant sludge/goo. It seems like some of that crud will not dissolve with any cleaner and air pressure will not dislodge it. So it needs a more direct mechanical cleaning.
I used this trick on my ‘37 to make sure the tube that goes through the head and feeds oil to the rocker arms was clean. I squirted a small amount of brake cleaner into it multiple times over a couple of days. I could see that fluid would drip through but seemed like it was still partially clogged.
So I pushed a length of “safety wire” through it. I made sure the the wire had many small offsets and bends in it. I would pull and push it back and forth in the tube. That loosened some of the crud stuck to the inside diameter. The brake cleaner flowed better but I still thought it should be more . So I chucked the upper end of the wire in my drill and slowly rotated the wire while working it back and forth. Boy did that really clean things!
I have every good flow to the rocker arms.
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