I won't speak to the Marine-specific requirements (TBS, etc), but from a CNATRA standpoint, it won't matter. You will have to do everything from scratch, except IFS. In effect, the credits don't transfer; CNATRA will look at you just like a stud with prior civvie time, and they don't "pre-designate" anybody, i.e., you won't automatically go helos just because you were helos. CNATRA requires everyone to go through the same track, API-Pri-Int-Adv-Wings-RAG. No skipsies, no cutsies.
Will it make a difference in the pipeline? Probably. You will most likely get the option to get on the accelerated track in Primary, and assuming no major fark-ups flying the Mighty War Weenie in the VT's, your being a prior helo dude will probably get consideration during selection. I don't know if Wing Five has an accelerated track for the HT's, but if they do, you will probably also get the option for that as well.
So, short answer: no, you won't get anything validated, but it'll probably get you through the program much faster.
Unless you have a major hard-on for the Corps, you might have an easier/faster time getting the Wings of Gold as a Coast Guard DCA. Those dudes are on a slightly different set of rules and they will let you go straight to the head of the line.