I just checked a block I had in my garage and the holes on it are much bigger and level with each other. Whether it matters or not I dont know There are lots of other places in the lifter valley for oil to drain back to the pan. I wonder if those holes in the front arent a for ventilation between the crankcase and the lifter valley or something? You know, so the oil will drain smoothly without bubbling back up. (you know, like leaving the vent closed on a gas can or on some oil drain pans)
I wouldnt think you should have to worry about them.