Wait, you took the ATP (no L in the US) written but do not have any FAA licenses? Does your employer know this? If not, you may in for a nasty surprise if they are expecting you to show up with an FAA commercial, multi, instrument.
My understanding is that you can't just show up with your licenses and get the FAA equivalent. However, you should easily pass them with your experience. This does though require you passing the written and practical exams.
How did you apply and get a job offer without knowing the requirements, if you are guessing that you need an ATP to fly a GII (you don't, unless the company requires it).