Actually along the quench and spark plug side of the pistons are the more critical areas to check the deck, because the piston does rock as the engine is running. I have seen engines with less than .040 piston to head clearance have the pistons bump the head. The way you are measuring it, the piston can rock .010 to .015 more out of the bore at these points and cause you problems. It also increases with more piston to cylinder wall clearance, so this should be checked after the block is finish honed to ensure a more accurate reading.
