B series heads?

I wouldn't let the "hardened seat" thing make my mind up. Induction hardening is only about .020" deep at the most. That's gone with the wind after being run 30 years and a valve job. Unless the engine is going in something heavy and or towing heavy loads, I wouldn't stress over hardened seats. Light hot street and race cars with low gears are about the last application I'd worry with hardened seats about.