attributing authorship and a time frame to any of the gospels is iffy at best.  any opinion at this point in time is speculation and there are many, many valid opinions from credible experts.  it does seem more "myths" are being found to be valid or have basis in fact. +++  some of the letters, on the other hand, are from paul...those targeting the roman demographic.  other letters were targeted towards different places- different languages and authors.   considering paul's relationship to jesus at that time...conversation most likely didn't happen. ++++ the lost books are not lost because of when they were written , but because of what they said.  they were written during the time all the other books were written -  along the same time span.  it was the pope and roman catholic church that decided what made the cut into the new testament. .. yes?.
   the whole concept of time has changed....over time.  time , itself, is a debate of Christian scholars. +++fascinating stuff for me...