Well from a real life perspective. When I was in the Marine Corps back in 79-83 there was a shortage of officers. My first platoon Had a Gunny as the platoon commander. And my last Unit a Headquarters Company/Platoon in which I was the Clerk (they found out I could type and was great with math) :P The Commander Was a former Navy Seal Officer 0-3 Lieutenant whose rank title became Captain, which Transferred, after going through some sort of Marine OCS/Basic/transfer coarse.( I think it may of actually been OCS with some additional courses for history and traditions. And the XO was a fresh out of Marine OCS 0-1 2nd LT. And our 1st Sgt. was a Master Sgt. who transferred from a supply unit into a combat unit. Could of wrote a pretty good sitcom with some of the stuff that went on at times. The CO was a really great Officer. I remember the first day the New LT. arrived after the Captain gave him the nickle tour, he then turned the LT over too me, as I was apparently for the last couple of months not only doing my job but the XOs (paperwork and such). So I got to train a new butter bar LT.
He was really cool about it and turned out to be an outstanding officer. Unfortunately I was not in long enough to see him get his O-2 silver bars. I was heading back to the civilian world. (in retrospect I should of stayed in)
I would if been retired by now and at least would of been a Gunny or Top heck maybe even a Sgt. Maj.
But anyways i got to rambling again :P
So yeh they would most likely be given a equivalent rank. I would think since most of the Airman and Sailors that were adapted into a foot or land unit in the army it would most likely be a technical rank like specialist for the enlisted.
There would probably be a placement coarse test consisting of basic physical fitness, mental condition, and skill aptitude prior to placement. If you were one of the basic seaman or airman with no special skill most likely you would end up as an infantryman. Though they would probably still have a brown water Navy back in the states where allot of the sailors would still retain their rank.