I haven't tried it, things would get a little tricky because I'm not sure that all the earlier B body drum spindles used the same wheel bearings as the later A-body spindles. And the A-body hubs were SBP, so they couldn't use the B-body drums. I know you can straight up use B-body drum spindles and drums and convert to BBP that way, but you need so many parts its not worth it and you can just buy the BBP disk stuff.
As I'm thinking about it, I don't think you can mix and match the B-body drum stuff with the 73+ A body drum spindles. There's a Viper disk kit that DoctorDiff sells, and depending on which drum spindle you have- '62-72 B or 73-76 A, there are different rotors needed. So different bearing diameters I think, so the BBP B-body drum hubs might not fit the 73+ A body drum spindles (even if some of the other brake parts do).
Viper Caliper Mounting Brackets for Mopar DRUM Knuckles
I love the FMJ spindles. Lighter casting, better camber for use with wide front tires. Already have them on my Duster and my Challenger though, think I have a spare set too.