[cypher]

With a Russian hybrid you wouldn't need so much height as an 8" wheel is adequate, I would be wary of making the cage too high, even with levels there is always a danger of falls so you would have to be careful how you set up the cage, also hams tend not to like having too much space overhead.
I would try to go for more floor space if you can, that sounds a bit on the small side to me.You might be surprised how much space is taken up with a good size house, sand bath & wheel alone as well as space for other things like hideouts, tubes or tunnels etc.