I would carefully cut the head off right above the collar.
Then separate the back of the head from the front of the head by removing the stitches that are holding it together.
This way you will get the entire front section including the seam allowance.
Hold the "old head" onto a window and place the new fabric over it so that you can see through the new fabric, and then trace the face and the hair carefully with a pencil.
Add a little to the neck length so that you can slip it back under the collar and then sew it back on to the doll.
Sew the head together and stuff it.
Using regular acrylic paint (in a little plastic bottle - from Michaels etc.) paint the hair, front and back.. You can trace the face using a permanent marker (always check on a scrap piece of fabric before using on face), apply a little rouge on the cheeks and you're done with the face.
After it is dry, stuff the neck into the collar and sew it up.
If you have to change the hands because of the different fabric, you can do it the same way.
It's not difficult, just take your time.