I have a carbureted 1986 Corvette L98 350 in my 83 El Camino SS that I am looking to upgrade in the near future. I am blueprinting the upgrades and I am trying to figure out the current compression ratio to see if I need to fit pistons into the budget. The pistons in the engine are flat top with 4 relief cuts for the valves that originally had 76'cc heads which equate to 9:1 compression ratio. I have 1987 58'cc Corvette Aluminum heads on it now with 4.125 bore, .039in. thick compressed head gasket size. I have found different compression ratio calculators on the web, but I need to know how many cc's the piston's valve relief cuts holds to finish the calculation. If anyone can help me figure out what my current Static Compression Ratio is I would appreciate it.