Chevy head I.d.

I've done a few searches on the web and havent came up with anything. I'm trying to identify what these heads are off of. Casting number is 10218885. The guy selling them worked for GM. He says they are 427. And the factory he worked for was throwing them out so he took them. Supposed to be a set of test heads of some sort. I'm not a Chevy guy and don't know much about them. Any Info would be great . Thanks

 

If you can't find the number then we'll need pictures....got any pictures?

 

the pictures arent the best

 

Don't look like a Chevy head I have seen, but I have only seen the older stuff. LS1 maybe? I can't find those numbers in my books.

 

Yep that is an LS head. They do have 427 cube LS motors maybe your confusing that with a real bigblock 427.

 

Looks like LS-1 to me also.