YES, they started making 1967 cars in summer of 1966. So yes many many have 1966 dated C 440 HP blocks. They all have HPstamped blocks from the factory. Engine code L in the vin means HP on the block. C body and B body.

Dart9ss you need to stick around and learn what the numbers on a build sheet mean. The 449 is the last 3 digits of the part number, not cubic inches.

C is 1967, it will say that in the top left corner your broadcast sheet. And the sequence number starts with C for 1967

And the part number is not always the casting number.

Can you post the broadcast sheet or fender tag so we can see dates and things? I could decode the whole car for you. No fee, no waiting, like GTs. LOL