We run a stock stroke 400 in my sons Dart. We use KB pistons and with the closed chamber 84 cc Eddy heads that we milled .040 we have 10.6 comp using the .039 head gasket. It works great as it is a driver street car that weighs almost 3600 with him in the car. And it has run 11.40's with 3.91's. Change the pistons and decide on the heads you want to use (closed chamber will be best) and then calculate the comp to see if any milling is needed. Its really not hard to get comp in a 400. Ron