Anybody have success retrofitting a '62 or earlier style drum to later self-adjusting style or disc brakes?

Check the ads in Mopar Collectors Guide, etc. Master Power Brakes has a kit that works with your drum brake spindles. Easy swap and modern parts. I have a buddy that has used it many times in different cars with no issues.

Just use later Mopar brakes from like a Volare or Dart etc.We were going to do the conversion on my kids 62 300.But he liked the 12x3 inch drums that were all new.They wont fit a New Yorker as they use C body brakes.Rocky

Used the spindle and brakes for a 79 Cordoba (73 and up B, any F/J/M body) to convert my 64 300, had to shorten the 64'a tierod ends to get the toe right. I think I had to use the 79's steering arm as the 64's wouldn't bolt to the 79 spindle. It has been over 20 years now so details are a bit foggy.

Spindle height was the same, ball joint tapers and diameters were the same. I researched the details before I started looking for a donor.