Although the Qur'an doesn't explicitly state that he is mentioned in pre-Biblical scriptures (like 7:157) or foretold by a pre-Biblical prophet (like 61:6) as prophets were sent to EVERY nation we can say there could be some references still existent in Hindu, Parsi, Zoroastrian, Buddhist etc scriptures - most probably (a) prophet(s) was/were sent to those areas where those religions originate but the revelation was not preserved in its pristine purity. There cannot be anything in Sikh scriptures about him being foretold as it's not a revelation as it is coming after the Qur'an although their Gurus probably say good things (and bad things?) about the Prophet (saw)?
What do think of the references - Naik has a lecture on the subject. It's something the late Ahmed Deedat didn't go into but I think the source text is "Muhammad in World Scriptures: by Maulana Abdul Haq Vidyarthi" - Advent of Prophet Muhammad (pbuh) Foretold in the Holy Scriptures. Do you know of other books, articles on this subject. Naik has read the book, accepted the material and then lectured on it. There must be objections by the scholars of those religions however. I have the book - it was published years ago.