Question about oil priming

Hello all;
Helping a friend with his weekend racer ('76 Duster 512" stroker bracket car, nothing fancy) I am in the process of repairing a valve train issue and in the re-assembly process. I was priming the oil system with a drill and having a helper turn the crank while I was operating the drill (counter clockwise obvs). I had a nice 80 PSI during most of the engine rotation but I noticed that there was oil leaking around the lifters on the #4,#6, only when they are in the lowest position in the bore. I am sure when the engine is running this is a very small duration of oil pressure loss just wondering if anyone has seen this type of thing. Thanks, Brent Nixon
The duration times RPM means very little becomes a lot. You might want to change lifters to solid body with no oil band..which is impossible with a hydraulic ..so here is where you buy a couple different lifters based on their pictures to find one taller and with the oil band ..lower perhaps