Have a pair of BBC 454 oval port heads. How can I tell if they are the large ports or small ports and if they have the large or small valves?

What are the last 3 digits of the casting #? It will be under the valve cover.
Eddie

let me know if you need a set of oval-port heads.i have two sets.one is 66-67 year,closed chamber.needs repairing,and a second set is opean chamber,68-70 year date.both sets are bare.both are large valve version.

like eddie said pull a valve cover and find the casting number
then cross reference the number here http://mortec.com/

Thanks, found them on the above link.