Change 8.25 rear axle to big bolt pattern

No 8.25 rears until 1973. 8.75 in 1972, so this axle (which would be SBP). Now if this is a whole 8 3/4 rear and and you swap it for the 7.25, that would be worth your while... there are several sources for big bolt axles for 8 3/4 rear ends. Would it come with the brakes shock plates, brackets? All different from 7.25 to 8.75, and you would get better rear brakes to boot if you made this swap.
What are the sources?