2 things, that 340 is not stock, or that 383 is tired!!!!!! I remember , i think it was 1995, my buddies 69 RR 383 4 speed, air grabber, 355 rear, all stock with 50,000 original miles never touched, beat up bad on a T/A chall. first 200 feet, it was even , then the 383 just walked away. and on the freeway, it was a kill!!!