Overfilling the crankcase might work, but it would need to raise the level enough to submerge the pump. Try the screwdriver in the drill motor trick first, and then add a few quarts of oil if necessary. Is this a fresh rebuild, or has the engine been run before with good pressure? I have seen oil gallery plugs left out after a block was pressure washed or steam cleaned, resulting in a wide-open path back to the crankcase for oil instead of a pressure buildup. If that oil passage isn't to the outside, the oil just recirculates back to the pan with no external leaks. The first time that happened to me, it was on a 283 engine my high school friends and I installed in a Model A coupe. We forgot to put the oil gallery plugs back in behind the timing chain when we rebuilt the engine.
Jerry
