This is going to be a Marines marketing wet dream, so I'd expect they'll want to use the KC-130Js, even if it wasn't the optimal choice - If they had their MV-22 refuelers working, they'd want to use them. If they go with the KC-130Js, I'd imagine that the USAF *might* detail a KC-10 (not a KC-135 - their basket-to-boom drogues could snap off at the most inopportune time,) just in case... Good thing this is happening now rather than a few years later when the USAF has retired its KC-10s (to afford to buy its F-35As.)