Whatever it is, and I'm fair
If it will run 24 locked out, set it that way.
Your plugs show additives, the reddish. Shell gas can leave that color as well but usually its octane boost.
If you look at the tang your timing is definitely as much as you can get. It's about middle but past the bend and toward the ring.
I dont see it being rich, but you can cut the threads off and see down where the porcelain meet the metal case, it should be brown/tan , not black.
I knew it.