Panic is right on the math. Just got off the phone with my 409 nut friend and he straightened me up. The 409 with a 427 crank (? bore) is a 447 and the 454 crank plus 0.060 bore gives 487. Turns out the 454 was the cheaper route because of the counter weights size. The 427 took way more Mallory (heavy) metal which is $$$. If one wants more detail PM me and I'll put you in direct touch with my buddy but be prepared for a l-o-n-g conversation when the topic is 409's. The head details alone are good for at least an hour. Be very comfortable if you ask about Roots type blowers and electronic fuel injection. He's done it all.
