Best to NOT heat the stud or Bolt.
Warm the iron block [ i leave mine next to the shop heater for an hour before hand[ . you really need the older style- cam-offset stud remover that has the nurled edge on the roller.
if it wont budge & you then finally break it off , carefully grind it level [dont mark the block] & start drilling accuratly from centre, starting with a Tungsten 3/16 drill & then one drill size at a time untill close [ use an engineers tap & drill chart-guide].
Finally ,use a new 7/16 nc tap to finish.
If you are accurate, & lucky, the new tap will chase the old stud threads out.
However you go about it , just be patient .