Anybody running 17" Cobra Bullit rims on a Duster

update I pulled the wheels off the car removed the drums ,axles and backing plates and measured the distance from the flange that the backing plate mounts to.Its 55 1/8 which looks like it should be a 68-70 B body rear.Is it normal to have 1 1/2 clearance to the leaf springs with this setup? I was expecting about 1/4 - 1/2 inch from everthing I've read.The measurement from the outside of the axle flange to the opposite side is 61 inches(is that what it should be?).From everthing I read this setup should center the wheel/tire combo perfectly in the car(not even close especially on thequarter panel side) I'm not about to remove the quater panel lip.
here's my setup
68 dart
suspension stock location
17 x 8 bullit rims 5.72 backspace
tires 245 45 17
anybody???????????????????