Oil pump priming question
You can have flow but the inability to build pressure with a stuck pressure relief valve in the pump, or a significant leak at the pump or beyond. So having flow is NOT a complete test. You need to now put the filter back on, and the pressure sensor, and see if you are building pressure too. From the original symptoms, it sounds like not... which would indicate a leak somewhere from the pump onward. So unless you can build pressure, then the pump and it's mounting to the rear main cap are not yet fully checked out, as well as possible leaks elsewhere.
Again, the pump's relief valve could be stuck open and you would still have some flow out of it, but could not build pressure Just being new is not a guarantee that it is 100%. Or it could be mounted improperly as discussed in earlier posts. The only way to see this is to take the pan off and remove the pump and check it's mounting for any gaps. Sorry....
Oil is sent to the rockers only occurs once per every 2 revolutions of the engine (IIRC it is every 2 revolutions, not each revolution), and then does not flow the rest of the revolution of the crankshaft. The rocker supply oil has to flow through some holes that line up in the #2 and #4 cam bearings and the cam journals, to get to the rockers supply hole. Refer back to post #5 for the crank angles at which this occurs for each side. You have to rotate the engine to these angles, and then maybe rotate the crank a bit each way to get the holes in the cam to line up for oil flow to the rockers.
It will take a while to oil oil at the rockers after you have reasonable PRESSURE to the pressure sensor location and the crank is at the right angle. So you need to have pressure at the oil pressure sensor before you can check out the rocker oiling. Focus on that first. A spun/mis-aligned cam bearing could cause no oil to one set of rockers or the other, but would not be the overall cause of low oil pressure, unless the cam bearing was just mostly or completely gone!