@Pretty3D SchoolHair for G8, please,...

Masterstroke

...for G3SchoolHair looses some of its features, when run through the auto fit process.

jestmart

Any hair, or any conformer, that has custom bones will lose them when Auto-Fitted.  The work around to scale and translate the hair to fit the figures head then parent it to the head.  

vwrangler

If you're comfortable with a few of the somewhat advanced features in Studio, you can also follow Sickleyield's tutorial for transferring clothing from G3 to G8; while hair is obviously not quite the same thing, the process works to preserve the bones and function in things like long ponytails if you want it to conform rather than parenting (if the shape you want to use is somewhat extreme, parenting may work better). I used the tutorial process on Fantasy Warrior Hair and Geneva Hair, and it worked just fine.

Note: if you try the tutorial, make sure you use an UNMORPHED G8F -- no Victoria 8, no other characters dialed in. Otherwise, it may lead to issues if you use the hair/clothing on shapes other than the ones you have dialed in.