As someone who has spent the last 36 hours of my life testing out 30+ different hairstyles on my Apollo Maximus, I need to say this:

No need to seek out special moprhs.  Just parent the hair item to Apollo's head.  Use X Y Z translation to position the hair.  Use X Y Z scale to get it to cover his head.  Then seek out the on-board morphs of the hair item itself, play with those to style the hair.

Do not conform the hair item to Apollo.  It is useless most of the time, especially if using ADS poses to change his look.

Eternal Hobbyist