well you can convert anything to dynamesh but only keep the detail and form up to a certain degree. it tries to project the best it can. afterwards you can deactivate dynamesh , subdivide and use the original as an inserted subtool to project its details some more. the reason i had to delete your subdiv 4 was 16 mil polys crashing zbrush when trying to project them.
yea i knew it had a lot of polygons, it’s awesome that you reduced it so much!