Welcome to PY! Here is a thread with pictures on what Jack was saying about engine codes. Check it out here:
http://forums.maxperformanceinc.com/...d.php?t=516425
Each year has different codes. I don't have a web site off the top of my head that lists all the codes. I think you can get a lot of codes from classicalpontiac.com and click on restoration. There are other sites too, and most guys here can help decipher codes for you too if you can't. Good Luck with your purchase....looking for any particular year?