Maybe there is an ignition cut when the temp rises too high... I never allowed any of my cars to get that high if it was overheating though... I hope there is no serious damage and that your heads and block remain true.
On the welded radiator note... I had plastic welded my old radiator in my ebony when it had a crack... I cut away the plastic aroudn the crack and started with good material to start with... Laid a bead in the channel I had cut. I then laid beads on both sides of this one for reinforcement. It held up well until it broke again. It turns out the head gaskets didn't fix my problem and the head was warped(im an ass for not having it machined I know
) If the head had been good, I would have forseen this as a perminent fix, or until it cracked somewhere else(****ty end tanks). Thats why I opted for the all aluminum rads from there on out
Tom