I found some other REAL HEAVY DUTY hubs from one of the karts in the bone yard (I believe they're from a Manco)- re-drilled for 4" on 4" bolt pattern, welded in some 1/2" studs and the wife took it out into the trails for a beating. I'll get some pic's of the hubs- I have no fear of these hubs!!!
Here's a short vid:
http://www.youtube.com/watch?v=85DTtoPy7kI