Going from bush Alaska to a multi-crew Boeing is a big leap. It can be/has been done. However, you will have a very, very steep learning curve that will require max effort. Even though it would suck, I think going to a regional (not RAVN) for six months to get your ATP, a 121 training program under your belt, and a little bit of experience would make your transition to the Whale A LOT easier. Atlas will most likely always be hiring for ANC.