Hi Bush,
Ya as I mentioned IBN KATHIR lived hundreds of years after the porphet Muhammad (pbuh), I don't know his references, but I am sure he used some of the translated gospels.
Theris a verse in the Quran that talks about the Jews them trying to kill prophets, I will have to find that.
Basically, I believe this is the reason why they wanted to kill him, I won't even doubt that they had to claim that he claimed he was God to even make sure no one would follow him from the Jews.