If by any chance you are doubting the lifters you used. Here is the TOTAL runout of the typical GM NOS lifters I checked. Why do I care? Ever see a pushrod that makes one turn and stops, then you give a twist by hand and it makes one turn and stops etc.? If the face is not perpendicular the bore that's what it will do as the offset contact point doesn't provide enough motivation for the lifter to climb the "high" point of the non-perpendicular face.
This not the starting picture ... this is the maximum runout I could find.
Forget what the crown was .. but I remember they were very, very consistent.
I also noted that the NOS GM lifter had a very pronounced chamfer on the face edge compared to the others (the Melling have the second largest), presenting a very smooth contact point to the lobe, unlike the sharp edges I have seen on many aftermarket lifters.
