Like tech said most ford manifolds are cut an an angle. when i do an engine swap i use a level to try to get the carb mounting surface level side to side and front to back . they work much better that way. If you end up angled, the boaters have angle spacer plates you can add to level the carb. I pitted on the 427 cobra that set the MIS lap record . with the the 427 tunnel port motor in the car it sat with the motor nose Down. we used boat angle spacers and regular spacers to have the carbs level and to equalize length from carb venturi to intake valve.