slant 6 rebuild and upgrade list

I don't think that they(hardened seats) will be in there. When I go to the larger valve setup, I understand that hardened seats are only a couple thou deep and can get removed if you go to a larger valve which is what I am doing. When we induction(rocklinize) hardened the tooling we used at work they were Max .005-8 depth before you hit softer metal...

The induction hardening goes deeper than that, but not sure how much. With the over sized valves you might be right to use the hardened seats.