I have 295 60 d15`s on my 68 fastback ,and didnt move the rear end at all....
inside the inner fender worked (from previous hemi days experiance) , front of fenderwell reworked to the inner fender panel "like gtx john said" , on a barracuda the shapes are identicle even by a template , inner fender lip rolled , cant tell it unless you get down and look , " wheels have to be perfect !" ...