Small update, the Vampire is assembled and ready to be primed. I've seen some out there that where not fully assembled for ease of painting... but I'd rather the model be strong than convenient.
Here is how I mount it: N24 magnet (same kind used on the Phoenix), and two brass pins for stability and strength. Simply drilled or bored out the space to fit the magnet and pins. No glue, tension keeps them in place.
Here is the mounting point on the Vampire. Carved out a space to fit the magnet, glued and greenstuffed. One minor detail though, the center of gravity is at the models weakest points. It's almost like no thought was given as to how a person was going to mount it.