1969 Dodge Dart GT “driver” build

I'm going to have to do a little trimming.
15x7 cop car wheels
215/65R15's up front
245/60R15's on the rear
So you've converted from small to large bolt pattern. That's where I'm kind of stuck. I'd like to do a disc brake upgrade and that would take care of the front. I'd need to figure out something for the rear. I have an 8.75 rear to install, I guess I'll need to pull the axles. Do you happen to know the back spacing on those cop wheels?