Hey Jimbo....you have your scales in reverse.At least it seems that way(I appologize if I am wrong).1/6 scale will put the skelleton at around 14" tall,1/8 will make it around 16" or so,1/12 will make it around 10-12"&1/4 scale will put it around 18".I have the Cinefex issue of Ray Haryhousen(an old one) and Ray built many of his puppets with the "build up method".This was done with liquid latex,cotton&soft polyurethane couch foam in some cases.Basically,you are sculpting with it.He also cast his puppets with a soft,polemerized urethane rubber and ran some with foam latex.Foam latex is "the work horse" of the stop motion industry and is still employed today.
However,many other people veer off and use the soft polyurethane rubber,or silicone.The products have changed&improved from 25-35 yrs. ago.Neither of them possess the properties that foam latex has(but close).However,they withstand the test of time where as a puppet made of latex will decay shortly.Latex rubber is very corrosive on metal,which is why the armatures are made of stainless steel,or aluminum.
Dragon Silicone is a great casting medium&has a shore A hardness of 10(very soft&pliable),has spectacular stretch/elongation,pigmentiing/tinting&memory properties.It is made by Smooth On,and the advertisements are sceen in Amazing Figure Modeler&the like.Smooth On has a web page as well(cant think of it off the top of my head,so try a google search).
I think you could sculpt(or re-sculpt on a kit) the skelleton if you want.Some parts will have to be sculpted&cast seperately like the jaw/head,ribs,hands&feet possibly&adheared on later.The basic armature could be of aluminum wire,unless you intend on making stop motion movies with it.