I agree with Flux here.
Also, PIC, when you say that 'a little loss is not much of an issue'. It's not much of an issue in a 'small' genny. However, 10% loss (don't know if this is accurate guesstimate; 90% efficiency I'd consider to be pretty good) of 6000 W is 600W. That's a lot of heat. Your stator is ofcourse a bit bigger too, but not proportionally, I think.
I think absolute priority is having a low stator resistance, i.e. as thick wire as humanly possible. And when designs are getting this big, I'd probably cast-in a little thermo-sensor as well. It gives you the option to monitor temperature, or just ignore if later temperature of stator isn't an issue at all.
About a year ago, when I started reading this board, the maximum seemed to be 14-15 foot. Nowadays 17ft is the standard upper limit, and there's already talk of 20ft. Wow... I wonder where it'll end.
But I'm afraid that the design is being pushed to its very limit here. There are limits to scaling things up. Looking forward though to hearing updates on that 20footer!
BTW, Sue & Harold, I assume you are aware of the Nirvana machine at Hugh Piggot's website?
Succes,
Peter.