After he went into them for the second time, there was a comment along the lines of those heads needing a ton of grinding.
After the third try, they’re still flowing less than aluminum SM’s that have had the seats cut and a minor quick blend in the bowls.
Plus the aluminum heads have a lot more spring installed height to work with, which makes it easier to set the heads up for higher lift.
It’ll be interesting to see what happens after he steps up to the bigger intake valves.
Although, I’m with Brian in not being a fan of running a 2.02 valve hanging out past the edge of the 1.970 seat ring.
Basically, I look at it as an exercise in trying to make “race parts” out of stock replacement parts, which almost always ends up requiring way more work than if you just started out with a more suitable part right from the start.