Comparing what you started with, it looks a whole lot better. I have never seen one that badly distorted.
In an attempt to be practical and honest, I can't help thinking that it needs more done to prevent further leaks?, but I'm a pretty fussy over-cautious person.
If you stop there, call it a day and fit it, there is a risk it will leech gasses past the gasket to the two uppermost, red circled bolt holes. I can''t say what the level of risk is.
At least the head would not be distorted again when bolted down to spec (unless the cylinder gasket face is not flat).
I can't be sure but I think those 2 bolts go onto blind holes?, so may contain any further leaking, but will make it difficult to remove them in future.
The 3rd red circled hole with the black arrow carries the bolt which I believe sometimes breaks into the Exhaust outlet chamber. That looks like it would be ok, as you have a small, clean flat face between it and the head chamber.
I understand/admire your self disciplined, marathon efforts to get to this stage, but it's your call really.
Maybe if you could continue at least to the point of obtaining a flat 'land' on the chamber side of those two top circled bolt holes?.
It may help if you place the head down on the paper and presuming you are right handed, place the palm of your hand (ball of your thumb) over the Spark Plug hole area, you can apply slightly more pressure to that area and less over the opposite end. You would emphasise more localised metal removal that way and still achieve flatness.
I don't think there is any issue with Valve (lift) Head clearance as a result of metal removal, but it would be worth checking anyway.
Just wondering if you have obtained/downloaded a copy of the K series Engine Service Manual?. It's very helpful.
Keep at it, you'll be rewarded with a better running Kohler in the end.