The 351-4V in 1969 came with an Autolite model 4300 carb originally. Only the 428CJ came from Ford with a Holley in 1969. Your original carb was 595 CFM I believe. It should be an easy carb to locate if you want to go back original. I think the best alternative carb would be a 650 Holley with vacuum secondaries for general use if originality is not important. Double pumpers can be tuned to work pretty well on the street too but are really designed more for racing use and will be a compromise most of the time on a street car.