magnum 500s on a dart?

They'll fit your car when you do the upgrades to the front brakes and rear axel.
What upgrades would allow the magnums to work? I have a '68 dart that I'm just starting a look at rims and didn't realize that the bolt pattern would be so different. What kind of a cost am I looking at if I opt for magnums or Ralleyes in addition to the rims?