1/4 mile times with a bb in a 72 duster

what it should run and what it will run are 2 different things.
get rid of the 5.13 's too deep.
take it to the track and get an mph run or 3, because I'm sure you will be traction limited, thus a slow time. mph with give you an idea of what the combo is capable of in et.
my 383 fastback has ran a consistent 11.45 @ 116