You can convert these with the free spin3d program it's a free 3d format translator that can convert the sto files to obj then just do a head replacement or patent the obj to a figure you morphed with the morph brush, I recommend you use map maker to create a texture template to make a texture these models don't have any textures.

I used photos to create textures for Michial 4 still working on the figures I have to create hand claws and feet still.