Back in the day 441 were considered the best 76CC combustion chamber stock GM heads, Then 487 or 993 (pretty even) followed by 882. These days however I personally wouldn't waste my money on ANY GM stock head. By the time you get new guides, bigger valves, Valve job, etc. Your way better off buying aftermarket heads. Personally I would go with alumninum for the SBC as they are not really much more than iron. The most economical alumninum aftermarket head will be better than any stock 30-40 year old GM head,