The codes on the head are:
CON9
3836848

L 5 7 (December 5 1957 Correct?)

https://drive.google.com/file/d/0ByJWVJFbAjpESXh1NW5OdGJEc2s/view?usp=sharing

Here are a couple photos of the rocker arms - does this provide a definitive answer to the year on them?

https://drive.google.com/file/d/0ByJWVJFbAjpETmJUa010Qlo2MTQ/view?usp=sharing

https://drive.google.com/file/d/0ByJWVJFbAjpEQWVEdHBCUmVRdFk/view?usp=sharing



The block casting code:
3769716

Date code:
C 28 O (March 28 1960?)

https://drive.google.com/file/d/0ByJWVJFbAjpEeHRRcGpzSkxpZlk/view?usp=sharing

Thanks

1951 Chevy P/U