In my previous post I asked if anyone knew the title of the cartoon that the initial model sheet (the elephant) was related to. In that, J Lee and Ken Layton answered the call: Mike The Masquerader. Bob Jaques took it one step further, and not only suggested that I post the cartoon, but then he actually had the nerve to send it to me (and thereby welcome me into the 21st Century, film clips online -- what a concept). Big thanks to all.
I did notice a bit of anachronistic chicanery: the model sheet is signed and dated 1960, yet the animation itself is copyrighted 1959. I went back and looked at the model. Although it's a stat, it appears that my father's signature and date are not. My guess is he received the model back from the studio the following year and signed/dated it then.