First, I made "plates" for both the upper and lower jaw, making sure they fit comfortably inside the resin head. Then, using Skully and reference pictures I found online, I sketched the placement of the teeth on the "plates". Using a lightbox, I then checked to see how the teeth on the upper and lower jaw would line up with each other (left). These would serve as "templates" for the jawset.
The rubber curing and then being removed from the Lego mold boxes. I sealed all the little gaps between the bricks with Sonite Wax **except** the one between the first row and the mold board, with the results seen below on the left. Brain cramp!! Little rubber Lego bricks! Fortunately the hot glue attaching the Lego mold box to the mold board kept the leak from getting out of hand, the worst effect being I didn't have quite the thickness of rubber I would have liked around the model at the top of the mold.