Will the rear axle fit?

Well, i have a '69 B-Body 8 3/4 in my '74 Dart Sport and all i had to do was cut off the spring perches and weld new ones on 1'' inboard on both sides. The brakes are new stock sized parts.
The car has 15X6 1/2'' stock rallye wheels off of a Cordoba on the back with 255 60 15'' tires.
When it was installed with the original stock saggy springs, it would slightly touch the sidewall to the quarter panel lip if you went fast over a bump.
I simply hammered the inner lip in (it is about an inch overlapped toward the tire) and there was lots of clearance.
Since then, i have installed Super Stock springs, so it's more of a non issue.
The inside offset of the rim is about 3 3/8'' and the tire is still almost 2'' from touching the spring, there is at least an inch to the inside of the quarter panel lip.
Getting a 275 60 15'' tire would be easy with the right wheel.
I would do it again in a heartbeat.........