70 duster 8 3/4 conversion to 4.5 drum or disk hardware

first let me say thanks to anyone taking the time to read this, i appreciate it. So my dilemma is this, I've got a 70 duster with a rebuilt 360, 904 tranny, and an 8 3/4 rear end, 4' lug pattern around.

I've bought the components needed to convert the front drums to disc using 73-75 a-body parts, but now I need to convert the rear end pattern as well. I plan on buying the axles from Classic Industries, but now I don't know what hardware I need to convert the brakes to the bigger 4.5 in pattern in the rear. I don't care about getting disc, I'm on a limited budget and only have drums back there is fine because majority of the breaking will be done up front with the new discs, but if the scavenged parts pricing is close, then I would opt for disc.

Has anyone had any experience with a swap like this, and what parts should I be looking for at the boneyard or online. I seemed to be having the hardest time trying to find some mounting bracket that isn't a part of some ridiculous kit. Can I source it from a junk yard car, or maybe piece a kit together from parts bought from members here?

Thanks for the help guys, really appreciate it!