How do I measure cylinder to see how much has been milled off???

I'm fairly sure any "as cast" surface isn't worth using as a reference point. They can vary a ton and even the surface features of cast metal can throw off a measurement enough to make a mess. I have not tested this - I tend to fit the intake "by eye" once the longblock is together - but I'm told the two machined surfaces to measure are shown in Bad's 1st picture... The surface spot faced for the last head bolt. Measure that thickness from the head gasket surface to the machined flat and it should be 1" if it's not machined. Again - with the varying casting quality, and the crazy factory machining I'm not sure that's 100% either - but I'd much prefer measuring two machined surfaces than try and make sense of any as cast surfaces.