He's doing an era-appropriate army for old school Tyranids, and trying to find a good counts-as option. It's actually a fairly common problem with folks who collect old school-themed armies; I want to figure out some way to make a Stormtalon or Hunter happen for my 2nd edition Ultramarines, but it's taking some doing.
I'd look at the epic Harridan for inspiration:
I think for this you'd want to get dragon wings and maybe a 2nd ed Hive Tyrant and see what you could do with that.
If you're feeling randy or spendy, you could try and convert them based on the limbs from one of the Armorcast Tyranids.