You need to understand that they all are correct, because this is the Beej Mantra for Jupiter or Brihaspati. Beej Mantras use the Sound vibrations for purpose of healing. Brim or Bheem or brihaspati or Brihaspataye are the same when you speak them, despite having differences in spellings. Spellings are not at all important the recitation of the mantras are what is important.
Blessings,
Navneet Khanna
Astrologer