I am planning on rebuilding the 440 in my truck and I have a set of 516 heads that have 1.74 exhaust valves already installed. I am curious if anyone has cc'd a set and knows what size the chambers are. I don't have the equipment to cc them myself. I am guessing they are around 80cc's? This engine has standard bore flat top pistons that are .070 in the hole and Summit's 6400 cam with .445 in .466 ex and 214, 224 duration @ .050. Running the numbers on Summit's compression calculator, gives me a ballpark figure of 9.6 using a .020 steel head gasket. It will never see anything over 5000 rpm. Also curious if anyone sees a problem with this combo for my street truck?