The slightly confusing thing about Banebots wheel hex hubs are that there are two sizes you have to select; the bore size and the hex size. For example, the nearest size hex hub that will fit on a GR-02 shaft (12mm) is the one with a 1/2" bore (12.7mm). But if it has a 1/2" bore, the hex size is 3/4", so you need to buy a corresponding Banebots wheel with a 3/4" hex cutout. A common mistake is to buy a 1/2" hub and a 1/2" hex wheel.

Using the 1/2" bore hub on a GR-02 means you need to shim up the extra 0.7mm to stop wheel wobble. Pretty sure there are some pictures in Gary's Boner thread as he used a thin piece of copper to fill out the gap.

And Max, those UNF hex hubs look ideal! Since they're a 3/4" hex, they should fit one of these for example: http://www.technobotsonline.com/bane...-shore-50.html
The only thing you'd need to do is find a way to stop the wheel from moving laterally along the hub, but a grub screw or collet could easily sort that out. Might get a few to try out with the Scot-Bots kits as it's potentially more solid than a melted plastic nut and allows for easier changeovers.