Tire/wheel sizing issues
And they never want to pay what it is worth. Try Craigslist. You're close to York. Should be a bunch of A-Body guys around that area that might be interested in the axle/rear end. Should be some machine shops in the York area that could shorten a rear end.
I've got a 64 Belvedere that has Cragars and BFG's on it. I tried them on the rear of the Dart a year or so ago. The Belvedere fronts were/are P215/70R15 mounted on 15x7 Cragar SS's, PN 61715 + 3 STD. They fit real good on the back of the Dart. The rears were/are P275/60R15 Comp T/A Drag Radial mounted on 18x8 Cragar SS's, PN 61815 -6 STD. I'm pretty sure that they fit like the setup I have now. Running into the spring clamp on the passenger side. They were close to the inner fender. That's why I didn't leave them on the Dart. I know -3 and +6 are the offsets but I'm not sure what they equate to.
I've got pictures of the Darts springs and inner wheel well area with the drag radials on it. Just have to find which file I have them in.