Not sure what it would do to the rigidity of the block, but you could deck until the chamfer is of a desired size then run thick head gaskets until you achieve the quench desired. On one of the 383/496 builds I was involved in, after decking the block to get it square, the pistons protruded something like .012" out of the block, so we ran some .050" thick head gaskets to prevent contact. It might have cleared at .027" quench, but we weren't going to risk it.