Bill,
I suspect that you will be despondent with the replies thus far..... So I'll attempt to explain why no realistic answer is available to your query.
If for example you were to build the standard Danb 10' hawt, your question can be answered fairly simply. If you use the same setup as the 10 foot danb, and it says to wind T turns of D diam wire for 12v, then for 120v you would just multiply T turns by 10. this would get you to 120v.... question partly answered. For the wire diam, you need to think that you need 10 times the turns in the same space, and so would calculate the smaller size accordingly....or you could increase the rotor diam to get more space between the mags and not reduce the thickness as much.... and calculate accordingly... I'd wind a coil of the 10X turns at best guess thickness and see if it fits..... problem solved.
However with out the baseline of the original mill you wish to change, it becomes a "how long is this piece of string in my pocket" type of thing.
The vawt complicates things further as no-one knows how big, what gearing, what mags, how many etc etc. so you can see there is no answer for you until you get a VAWT that actually works, and you have some fair idea of it's revs, torque (for probable gearing up) etc.
If you had a 12v VAWT that worked, you would simply multiply the turns of that mill by 10 (or whatever volts ratio ( volts wanted/volts original) you were after) and decrease the wire size to fit your winding space.
So how long is this piece of string I'm holding up..... see the difficulty now?
Hope that helps ease the pain a little
........oztules