There's no problem having an aquila for Grey Hunters. They're still Space Marines, and they still revere the Emperor. The old Space Wolves sprue was nowhere near as all-encompassing as the current one, so it wasn't uncommon for 3rd/4th ed Wolf armies to have lots of vanilla Marines with just a wolf tail or Space Wolves head. I know because I ran said army
If I were you I'd get the new Wolf pack, build the 10 dudes in it, and distribute the leftover bits (of which there are a ton) across all your other models.