Originally Posted by
Javelin
I'd say it's pretty safe but not a piece of cake. Immigration could easily take 30-45 minutes and the non-Pre-check line could easily take another 30 minutes, and that's not including baggage claim and rechecking. If OP gets lost and takes the wrong AirTrain (note to OP: take the yellow line), plus somewhat typical long lines, there'd be no margin left.
Last I checked, one does not need to clear immigration and customs when arriving at JFK from LAX!