I'll give it a crack too, prolly sculpt the others first then. I'd say the big guy is no bigger than 6", prolly about the scale of the SW Minis Rancor (which is 5"). I'd say that would be a good scale for a real board.
I'll scale my figs at that scale and maybe see if MonCal is willing to do the resin pours. It'd be awesome if we could make them posable, but I'll concentrate on the sculpt first.
Not out to make money on your idea - If I can do them and you like 'em, we'll do 'em at RPF bargain prices.