i have change my waterpump and my thermostat need to know how big a v 8 raditor should be my raditor is about 1/2 in thick should it be thicker

What you are calling a half inch radiator, I believe is a transmission fluid (oil) cooler. It sits in front of the rad. You flushed the antifreeze and changed it? Changed the water pump and thermostat. How's the timing? What about the muffler - when has that been checked?