I was thinking pretty serious about pulling the trigger on those but I am a ways away from doing anything to my 318. I have a pair of 302's in the garage that need rebuilt. I know it will cost me more than the ones you bought.
Mike,
You've got 2 cores worth $100 to Rock Auto, when they get more in. Do you want to work on your own heads? You could still take their rebuilt ones apart to port them or whatever.