A friend gave me a pair of "049" oval port big block Chevy heads that supposedly were gone through by some owner previous to him. I plan on using different valve springs to match my cam application, so I'll be pulling the valves and looking at the seats also. These heads were supposedly freshened up, so hopefully I won't have to spend a bunch of money on them. While I am looking at the valve seats, how can I tell if they are the original, non-hardened for leaded fuel seats - or, if they have been replaced with hardened seats so that todays fuel can be run? As always, thanks for the info!