A ramen egg is very specific with the white fully cooked and the yolk just so. Unfortunately, there is no single temperature at which this happens.
To get the yolk done, cook at 150F for 45min and to get the last of the white done put the egg in a pan of actively simmering water for one minute. You don’t need an ice bath, the heat does not penetrate very far but it is enough to get the white finished cooking.