I understand that although it bolts in, the housing (and by extension the track) is a tad wider than the A-body, so the axles would not be the same length. That swap is perfect for someone needing to upgrade to the big bolt pattern though. The width difference is so minimal it shouldn't cause tire clearance issues, and best of all the spring perches don't have to be moved.
Did this on my 72 dart. Moved the perches a half inch on either side and also had to get custom backspaced wheels do to being slightly wider. but well worth it compared to the high cost of A body 8 3/4.
