It’s not a complex system and there is not much to go wrong . Wiped out cam bearings might do it but that is rare. You must have made an incorrect assumption somewhere like the rocker shafts being installed correctly. Pull the rocker assemblies,plugs, distributor and drive gear and spin the pump cw using a drill and priming shaft. You will have to slowly rotate or bump the crank to find the top end oiling positions. The oil should shoot out of the heads.
