OK so you are OK up to here: >magsnarl1 has 7929 vertices, and when i grab the head, hit >add morph target, and import it back in, it takes fine. What I suggest is once loaded set the morph target dial to 1. Then export the head only from Poser. You could use the export as morph option. Then import this to RDS and fine tune and export as .obj from RDS and load this as a morph target, that should work.