Congratulations, Nice score on those heads, I’d like to get some of those myself! The steel crank ain’t bad either. Some say Chrysler started hardening the valve seats sometime in ‘67, but I haven’t confirmed this myself.
I have no knowledge about the seats in 67, but I think that is a bit early for that. As I recall, hardened seats started happening when the lead was removed from the gasoline. But as usual, I am probably wrong.