I mean, I know there was a point in the early to mid 70s, where they started hardening the seat areas, when leaded gas began to be "watered down" so to speak, as lead in gas started going away. I'm thinking that if the virgin head material is simply ground away to fit O/S valves, that the hardened layer will be ground away, and valvs will sink into the head. I'm looking for 100K+ mile durability out of this engine, 3 season daily driver kind of thing. NOT a "weekend warrior" that just goes to swaps and car shows a few times a year.
