The crumb

30% whole wheat, the rest strong white flour. 70% hydration, no mixer just stretch & fold 5 times 30 minutes apart, rest until puffy, split into loaves and rest overnight in lined baskets, covered with plastic bags, in the fridge.
Bake next day in hot cast iron (you can see it in the picture) this time 450F for 20 minutes closed then 30 minutes open.
This (or slight variations) is the bread my kids call THE Sourdough.
I start with a kilo of flour for 2 loaves, 700-750g water, 200 of starter, so a little bigger than yours. My dough seems to rise so much better when there is a lot of it.
Also I do start with very cold dough into the hot pan. Like I take it out of the fridge at the last minute, score and into the pot. I cannot score room temperature dough.
But yeah. Either 45 min at 475f or 50 min at 450f, it is really nice & soft inside with a very hard crunchy crust.
Cool, thanks for the details.