'64 Dart+8.25" rear+17x8s=???
Front rims are Chrome Bullitt Wheel Mustang 94-04 (17x8 )
Rear rims are Chrome Bullitt Wheel Mustang 94-04 (17x9) the rear rims are +24mm with a 5.95 back space.
I'm also running rear disc kit from Wilwood, Not sure if it changes the offset if at all.