Seems to me that if you have to ask, then there is an element of doubt, and that's not what you want 35,000 ft above the Pacific. As a matter of fact, so soon after a tx, I'm not sure I'd trust airplane food at all, first class or any class. The last thing you want is to get sick in the US. I hope you have travel insurance that covers medical expenses incurred in the US with at least a US1,000,000 limit. You know how expensive health care is over here. And in your travel policy, you might want to make sure it covers evacuation back to Australia.
btw the day I remind anyonf of a French Woman is the day I know the transplant is doomed!
(The one food I would avoid on health grounds is raw oysters, but thousands of Louisianans would tell me that life is meaningless without trips to the raw bar, so there you go.) Oh, but that insurance advice is pitch perfect. Please heed it.