FlyBy,
I agree with XL. You obvivously have the experience, but overcoming the obstacles mentioned are the biggest deal. Then of course, you'd have to start at the bottom of a lengthy seniority list, assuming you could get hired.
One way I know of that may work for you, if it's still happening, is Ryan Air. (not Irish Ryan)
They are an FAR 121 Carrier with no real seniority list, and they hire and furlough as per company needs. ALPO may put an end to this soon (and rightfully so) but I know in the past there was some sort of dual operation going with 737-400's. Half year in Europe, half in the USA. They hired direct into the seat. The US guys got to fly in Europe, so it must be recripocal.
A good source for this is Brookfield Aviation ask for David or Bernie. They were doing this op a few years ago. Don't know if it's still going on, or if it includes the 320.
Hope this helps.