When I got my '62 Galaxie back in 2005 or so, it had what I was told was an original motor in it. Later down the line I pieced together it was a '64 era dealer replacement shortblock with OEM '62 top end on it...anyway, never had hardened seats in what I'm pretty sure were OEM '62 factory heads. There was a jug of lead additive in the spare tire well and the prior owner told me to use it religiously, to which I immediatley forgot. I had a valve job done shortly thereafter and the machine shop asked if I wanted hardened seats installed. I forgot about the jug of lead additive and figured, "hell, if they aint sunk already, I'm good!" and didn't have the hardened seats installed. About 10k miles later, the motor started feeling pretty tired. It had 90k on the odometer. When I tore it down, it was pretty worn and ready for a refreshening. Oh, and half the valves were sunk into the heads...some worse than others. I'd have the hardened seats installed in whatever heads you choose to run.