my personal opinion, get the AFR's but skip the 345's and get the 357's. they are a great head. I ran them for years trouble free and awesome power out of the box. They had better power than a set of 355 cnc darts that I had before them. I had my heads on a 572. a friend of mine runs them on a 555 bbc and had the motor dynoed at 945 hp at 7600 rpm with a single carb. You won't be disapointed.