Join Date: Sep 2008
Location: Fruitland Park,Florida
Welcome to the forum.
While there is plenty of factory lt1 head info out there, aftermarket heads are another story. You can hope someone out in lt1 land has the knowledge you need.
Or you can start researching the different companies who have made aftermarket heads for the lt1. It is that company that made your heads which might be able to translate the casting numbers on your heads.
Sorry I can't help you out any more than this. But the newest lt1 car is now 22 years old. The aftermarket companies have pretty much forgotten the lt1, which had only a 6 year production run.