Here is a link to Mortec:
This section has casting numbers I have put together over the years as I worked my different car projects. Earlier I had also included Chevy Numbers I had copied off a site called Mortec that had gone offline for a while. Mortec is now back online so I pulled their information off of this site so they could get their deserved traffic. If you are looking for early Chevy casting numbers for Big Blocks and Small Blocks as well as Holley Carb info, be sure to check out Mortec.
Below are links to the pages that I have researched and created: