It could be any amount decked off that they thought it needed.The one I had fit perfect with no gaskets,so I measured the gaskets I wanted to use,at .030- what I thought I needed for gasket compression.I had .027 cut from each side for a perfect fit.
According to the M.P.crate engine book,they were supposed to be set at a certain deck height,but the "908" shortblock I had(also from Cummins)had such terrible machining elsewhere,that I would not trust what it was "supposed" to be.