Yeah that was my take also, after the second post. It can be overwhelming when that happens. I was taking one off and saw 3 big plug style Allan heads. Searched for the right socket for 3 days to discover they weren't bolts. I missed two down in the timing chain assembly. Now that head is getting plained as I didn't follow the sequence right.

Heat from the weld should probably be cautious too. I know I've attempted to dissipate the heat elsewhere in those situations. wrapping a piece of copper around the head. Sliding some aluminum flat stock against it. Etc.