It looks pretty decent to me, I'm a bit baffled by the window size thing, I thought they were all the same - I'm sure they are on my model. what does want doing though is to lose the radiused internal corners of the windows, they should be square, this looks like the old K's kit of yore. Also, bring picky, the edges of the strapping look a bit lumpen and would benefit from some work with knives etc to make them thinner. Both pretty easy jobs I'd have thought.
If it's G3 then it's really going to challenge your box file layout....
I reckon it will make up into a stunning model with a bit of work, which I'm guessing will be less than that required on the pesky brass thing that kicked this thread off!
Simon