When customizing a sex doll, please note that the size of the doll head varies. View the pre-made doll and then see in the picture which size of the body your preferred head matches. That will help you find an idea of the head sizes.
For example, if the head you like is paired with a 140cm body, don’t stick that head on a large, tall body. And if the head is matched with a 170cm body, don’t stick it on a small body.