how to guide for 7 1/4 to 8 3/4

Start soaking the bolt a week or two before you are going to swap them out.
Take the tension off of the emergency brake cables, and un hook each emergency brake cable.
Un hook the rubber brake line where it comes down to the rear axle.
Remove the four bolts from the drive shaft.
There are four nuts on the front of both spring hangers, and two on each rear hanger, remove them for each spring. Pay close attention on which way the front hangers are oriented, if you switch them from side to side it will lower the car 1".
The rear end is now ready to take out of the car.

Your brake drums, brakes and backing plates will bolt right on the 8.75 axle, this will give you big bolt pattern brakes, and most likely 2.5 x 10" brakes. This requires the use of Dr. Diff axles.

Download the factory service manual which will show everything. The manual is a sticky somewhere on this site.
It is really pretty easy if you know the basics, and have a shop manual.