I built and flew a SS2 model. 1" diameter with a 13mm motor mount. Goes about 300' high on A motors. I think it's the first flying SS2 model out there.
There were a lot of concept pictures and such out months before the actual ship was unveiled. Mine's by no means a perfect scale model, and the huge eye pattern is well-nigh impossible to recreate, but it looks pretty good.
I used about half an ounce of nose weight and it's very stable. The nose cone is an Apogee cone; the tail cone I cut myself from an old broken cone. I wasn't able to recreate the cockpit bump on the nose.
It's about a 1:90 scale. The SS2 is about 60' long, with only 16' of that actual cylindrical body.
This post (from my bloggy blog) has basic scale information, drawings, and a discussion of the "DNA of Flight" - the drawings of aviation milestones on the spine of SS2.
The one problem with the SS2 is the small nozzle on the original - just one-third the body width. That means a 1.5" rocket for a 13mm motor, 2.2" for 18mm, 2.6" for 24mm, or 4" for 29mm. Even a half-width nozzle like mine is somewhat underpowered.