By the book, the stock main jet size for a List 1379-2A Holley 2V is 48. That particular carb is indeed listed as being for a 1957 Ford car with a 272 V8. The earlier in the year 1379-1A carb (also for a 1957 272 V8) shows to have 52 jets so there’s a difference in the air bleeds of those two carbs. Both 1379 carbs show to have #65 power valves.