no oil on rocker's drivers side only? 360 magnum

the engine was a running/used engine that he pulled and sold the truck it was in. I pulled the intake and made sure the galley plug was there. I got brand new lifters and the same thing. I put the lifters in with the oil holes facing down(towards the center correct?) When I got the engine I was told that the heads were la's converted to magnum's but after looking at them, they are clearly magnum heads on a magnum block. That being said I know I installed the la head gaskets. Could there be a oil passage that is being blocked by the headgasket. thanks for the help guys.

No, the head oils through the pushrod not the head. The left lifter galley is fed from the #1 main bearing. A couple things come to mind, you can check them in any order you see fit. First is maybe a spun #1 main bearing, but that would soon wipe out #1 rod bearing as well. Next would be the soft plug behind the cam retainer plate. It may be non existant or could possibly be pressed in to far blocking the feed hole to the lifter galley. Then of course there is the plug at the back of the left galley inside the valley but you said you already checked that.