Hi,
Welcome to the site!
You're going to need to look at the engine block to get the engine code. It would be on the front of the engine block on the passenger side just under the head. This link might help you: http://www.yearone.com/yodnn/tech/Vehicl...23/Default.aspx
It should be a two letter code. Also look for the casting number on the back next to the distributer, those numbers will be able to tell us the year.
The 8th place in your vin will be a 1 or 6. 1 indicates it was a 8 cyl, 6 means 6 cyl.
Here's a link to decoding vin: http://www.firebirdnation.com/search_tools/vin.php
Let us know what you find out!