John,Normally you can simply crank the engine( connect the 30 and 50 terminals on the 3 terminal junction box by the battery) with the cover off and the ignition unplugged from the box the oil should /Must pump from the spray rail. If not,there is blockage. This is because the oil flows via the crankcase to the rear of the engine and then up to each head. If the rear most bearing is Not leaking oil from around the cam journal there is a blockage in the block or head.It should also pump freely from the spray rail hole in the rear most cam tower. To rectify this He possibly needs to remove the head and clear out the oilway.
It sounds like he has the same problem as me with bits of filter blocking the oilways.