Double hump head question

[BoiseSS]

For those in the know. I just got a pair of Chevy “Double Hump” heads. The casting number is 3782461 with a casted code of C6 over the top of the number. I looked up the number and there are two different specs for that number. 3782461 is a 62cc chamber with 2.02 intake, then another 3782461x is 64cc with a 1.94 intake. My question is, is that x supposed to be casted in and is that C6 mean it’s the x?