If the lifters are not in place in the block there will be no way for the oil to get beyond the first lifter bore. That big groove around the center of a hydraulic lifter is how the oil gets from one bore to the next. Put a lifter into the first and last hole in the block, run the pump, and keep adding lifters two at a time. I'll bet you get oil flow all the way to the middle of the block that way. If you do, the problem with collapsed lifters is with the lifters, not the oil supply. "new" doesn't necessarily mean "good" and new 235 hydraulic lifters are notorious for failing to stay pumped up.
Jerry
