LR photo studio (views models, can export/import meshes)
TMC bone tool for fixing bones
TMC polygon import tool for importing TMC meshes that LR studio fails at.
TMC texture tool jpn custom version
easy mode: export the new meshes and textures with LR studio, open the old "with pubes" mesh in LR, import the new body over the old (body and pubes are seperate subobjects). then replace the old textures with the new.
if it doesn't fit right, then you'll have to start messing with blender, which is not as scary as it sounds.