4 wheel disc help?

They should fit just the same on an 8-3/4" :dontknow:
In the mid 1990's I swapped in an 8-3/4" rear into a 1970 Charger we had (original 318 auto car; we ran it with a 354 HEMI & A883 4-speed transmission) I used the entire original drum brake set-up off the 8-1/4" rear (or was it a 7-1/4"? I forget...)

There are a couple simple reasons why I went to rear disk brakes:
1.) My original drums were shot (not even working; everything was junk) and would have cost as much to replace than converting to rear disks.
2.) Disk brakes are fast/simple to work on/replace.
3.) Maintenance free (no adjustments) once set-up.

It all added up to a no brainer to me.
Also high speeds & water will not affact a disk like they can a drum brake set-up.