usually you pre heat the cast..then slow cool in sand..you taking the box apart first?
didn't have to. got it back today from a local welder with many years of cast experience...got lucky :p
He didn't try to bend the ear back to re approximate the crack as that probably would have snapped the ear off. He V-grooved the crack and welded it up with 99% nickle rod after preheating the area to 350*. 1/2" beads at a time with peening during cool down after each bead. It worked great. I then was able to re-machine/flatten the mounting surface with fine grit wheel and big, flat mill b*std. Paint drying now, should get it all back together in the next day or so.
It was interesting to learn from this guy...said the Japanese cast is actually better than a lot of American stuff...called it semi-malleable cast as it will give a little more than other cast. In this case 1/8" was too much so...crack :p