Wasn't the point of the sub-plot in American Graffiti, that the flat-head drag racer knew his days were numbered when the out-of-towner with the new over-head valve Chevy (Harrison Ford) had him beat until he ran off the road? Of course that flat-head didn't have a super-charger. To me the most memorable scene was when he pulled it out of the garage and the kid said "you got the __ heads on", which he only used for racing. Only on a flat-head can you swap heads in 30 minutes. Even if they aren't the fastest, you have to love the old school hot rods.