As said they are both pretty simple. You would be able to swap jets on the holley & iirc all carter primary jets are the same (other than orifice dia) so you could swap jets. You might inquire over at www.slantsix.org as those guys have dealt with them almost exclusively for decades. Doug Dutra and Chuck Rivers would be 2 good guys to pick their brains on that question. EDIT I just remembered that AVS pri jets are tall jets for the 3 step rods and AFB used shorter ones & these might be the ones to use or Eddy jets which'd sure be easier to come by