It depends on your the size of the deck height and cylinder bore on the block, stroke of the crankshaft, combustion chambers on your heads, and the compressed thickness of your head gaskets.
My advice is to find an online compression calculator and enter the appropriate values to get accurate estimates.
My build started with a Dart windsor block with 4.125 bore, a crank with a 4-inch stroke, 58cc AFR heads, and FRPP head gaskets. The computed compression ratio was 10.49, but the heads required some minor milling, so I'm expecting something closer to 10.6 or 10.7. I won't know for sure until the motor is done (sometime next week).
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