the only header that fits the a-body with the low deck from TTI is the 1 3/4" primary with 3" collectors. i have these on my 67 dart. fit great but i am prob giving up a few hp with the tube diameter. you can run the hooker fenderwells. they come in 2" and i think 2 1/8". or if you can find a pair of proparts headers they are 2" under chassis