Unfortunately John’s chart only gives the cubic inches for what happens when overboring and/or stroking. There are at least three different big valve head castings with the advertised cc’s being between 69 and 82cc’s. I'll add at this point that the advertised cc’s is the best case scenario and many times the actual cc’s will be somewhat larger that these. To accurately determine the compression ratio, the head cc’s and where the piston resides in the block needs to be known. Add to this that the head gasket manufacturer and composition plays into this along with how much the heads have been milled.
Here are some of examples of how the CR can change with the various heads and/or machine work. A best case 292 at 0.030” over with the flattop pistons at zero deck and a set of big valve ‘G’ heads milled 0.020” with a Best Gasket head gasket will be right at 9.0:1CR. Using a set of big valve ‘113’ heads on the same combination that are nominally larger than advertised to begin with and only milled 0.006” will give a CR of 8.15:1. Using a set of big valve ‘471’ castings and assuming they have the stock 82cc chambers (could be nominally larger) will drop the compression ratio to 7.6:1. Dropping the piston from zero deck to 0.027” in the hole and the compression ratio automatically drops another half a point or what was a 9:1 engine suddenly becomes an 8½:1 engine. Put a piston with a 10cc dome back in the engine and you can pick up just slightly more than a full point in compression increase so there are several ways in which to manipulate the CR to get it exactly where you want it.