Jeep Cherokee 8 1/4 to an A body ?

saw the topic in the brake section of this forum on fitting Jeep Cherokee rear disks to a 8.25 rear, as I plan to replace the stock 7.25 on this 68 Barracuda with an 8.25, that looks to be the way to go. Found two Cherokee candidates in the local pull a part,, I don't have the 8.25 rear so,, instead of just the disk brake package, should I get the complete rear axel and diff? Did not think of this at the time, so I did not measure the Cherokee flange to flange, does anyone know how it compares to the 7.25 width. Certainly I'll have to fix the spring perches,, would this work?,, anyone know what ratios were used in the Jeep Cherokees?

thanks