I have a 65 Impala w/ 4.56 posi. As you can guess, the highway is no longer an option!! Ill be building a 496 which i hope to get around 550-600 hp and the same torque. With that in mind, would I be better off using a bowtie overdrives level 3 700r4 or 2004r? Im more concerned that the larger gear spread on the 700r4 might give me less performance with the radical rear end. Any sugestions?