Body Comparison Show me 60cm girls with small hips

Have you seen the Resinsoul 60cm body? It may fit what you're looking for.
Their website is slightly incorrect though -- this girl is 60cm WITH a head (I have the body and just measured)

 

Are you looking for a specific measurement range (e.g. up to XXcm) or slim in proportion to the body?
The current trend in 60cm girl dollmaking seems to be towards large hips/prominent buttocks.

The height of your hybrid is also likely to vary by a few cm depending on the neck length, the size of the head, and how the head sits on the neck, which means a 60cm girl body with one dollmaker's head on may not be exactly 60cm with Rexy's head – I have dolls with identical bodies that have some height variance because of how their different heads are sculpted.
Iplehouse bodies are known for having a "mushroom top" that may also affect how a head designed for them sits on any potential hybrid bodies.