IMHO, one doesn't belong in the cockpit of an airliner, conducting 121 ops without an ATP, or, at the very least, a single-pilot multieng 135 letter (very similar checkride). I suspect with less than 300hrs, there are plenty of SINGLE engine airplanes that would eat you for lunch. I don't mean to insult anyone, but ask yourself: Are you confident enough in your abilities that you could ably fly say, a PA-31 (or, for that matter, a turbo Centurion) on a dark and stormy night with several instrument approaches close to mins? I wouldn't expect you to answer in the affirmative to such a question - with 300hrs. But a person in the cockpit of an Airliner Should.