Hello!
You might want to take a look here:
http://www.fireballmodelworks.com/military_main.html
I'm not so sure, though, if decals for a short huey can be found there. There's always another chance - to get a scan of the original kit decals and to redraw them in, say, CorelDRAW!, and then custom print them. That's what I did with the decals for my EKA-3B (with modifications) - and got very nice results.
Hope it helps, good luck with your rebuild and have a nice day
Paweł