I know someone who has had a XD2S engine overheat and warp the head. Everything "looks" okay down the bores. The head has been planed and refitted but the cooling system is being pressurized. New gasket, new bolts, etc. Before the search begins in ernest,

Is there a typical place where these blocks will crack in such circumstances?
If so, how does Chemiweld go?

Has the top of the block been known to distort as well as the head?

Any helpful thoughts from someone who has experienced this may narrow the search and avoid a big job.