I'm curious about your cam gear. Did it come off the end of the camshaft as one piece, or did it fracture and break apart? You had to remove the cam and have a new gear pressed on, right? Did anybody check the condition of the cam bearings?
The truck is a '47, right? But if you have a 235 that has 30 PSI oil pressure at idle, you prolly have a later model engine, from '54-'62. No 235 motor ever had full-flow filters. They have either a bypass system that uses a drop-in cartridge, or no filter at all.
I think Fred T is right, the oil flow in a '54-62 235 is from the pump to the mains. At the rear main it splits the oil to the rear cam bearing and the #6 rod bearing. I'd also have to double-check this.
Does the engine knock all the time, or only under certian conditions?
Bad rod bearings usually knock most of the time the engine is running.
Bad mains can cause low oil pressure. They will knock at idle or low speeds, or when the clutch is pressed in.
Bad cam bearings cause low oil pressure and some valvetrain noise. I have seen bad cam bearings drop an engine's oil pressure, which then makes a marginal crank bearing go to knocking. Improperly installed new cam bearings will also cause similar problems.
Bad oil pump relief spring can cause erratic or low oil pressure, but it isn't very common.
Plugged oil pump pickup can also cause erratic oil pressure.
Let us know what you find.
Good luck,
Chip
