On a virgin block with extremely tight clearance you may not have a problem for a while, but this would not be typical of most builds.
That is why almost every sbm performance article directs the builder to restrict the oil to the lifters by one means or another.
But those lifter bores with the chamfer are so close to the giant oil feed hole that as the bore accumulates some normal wear, and with so little surface area I would think they would leak more than a block without those chamfers. IMHO
