72 scamp rotor fittment issue

You gotta be having trouble with those hubs & rotors not being centered on the "shaft" of the spindle.
And that would have to be the races in the hubs.
Did you check them to see if both inners, and outers, are seated correctly?
Did you remove the bearings to pack them with grease, when you took everything apart?
If so, did you use a punch to punch out the inner bearing and seal, or did you just use the spindle nut on the shaft to pop out the bearing and seal.
Make sure those races didn't move in the hubs.
That's the only thing that would keep everything from being properly "centered"
Well, anyway, hope it helps getting you out of your problem.
Jim V.