I recently purchased a 1971 402(396) chevy big block to replace the one I blew up in my chevelle. Was wondering if I should use a domed piston in new engine or a flat top? Was also wondering how to get more horse power out of this engine, if the bore and stroke are the same as the older model engines why is my horsepower lower? The valves are bigger in the 71 engine than in my 70, so why the horsepower difference? baffled in ohio