Will a 66 b-body 8 3/4 fit without cutting?

Go for it - I put a 66 B body axle in my 73 dart sport. You can get offset wheels made up to meet your backspacing needs, no problem with steel wheels I had mine custom made. I easily fit up 265 50 15's within the wheel wells and no cutting the pinch weld. I moved the spring perches to match the A body spacing.