What they did is commonly referred to as "chamfering". It's done to most if not all of the
oil holes in the block. Especially where the
oil filter adaptor bolts to the block, extensive chamfering required there.
Chamfer and de-bur are often done together. De-bur is simply removing any rough or sharp edges that under stress may be the starting point for a crack.
Align bore? Gessford leaves NOTHING to chance!
Heres a pic of my chamfered and de-burred block. Note how LONG the chamfer is for the
oil filter adapator.
