I looked and looked and couldn't find another sensible answer to the Lady Knights problem. The only variable is the heads, really. Helmets would have been nice, but too much extra work.
As for the dragon (the pale green one) the base he is on is 75 x 50 mm A chariot base is only an inch longer, and the head of mine overhangs the front of the base by half of that, so it would be fine on the chariot base with a bit of extra decoration.
Strangely, the model is naturally curved, and would actually look okay on a square base. I think you could make it "longer" by changing the bend in the neck a little - the tail would be harder. It's a nice model, worth getting hold of and using.