Disc break conversion kits?

Yes, except the FMJ spindle warning.

Find 73+ A body BBJ upper A Arms and a set of discs from a 73-76 A or an FMJ body car. They all work well if you are swapping to big bolt pattern wheels.

Small bolt pattern, factory Kelsey-hayes or scarebird work.

Oh so true. I keep forgetting about that spindle war thing. Big Block Dart has the graphs and all that info on the FMJ spindles. Heck, it's what I run on my Valiant. :D

The Mopar Action tech article is still probably one of the best resources for us on the interweb. Spindles not withstanding....