I used Auveco 808 clips and the bottom rail support. Small angle brackets with nutserts on them for the armrest, then ran a 10/32 through the bottom of the armrest to attach the armrest to the door.
@Warren Wing thanks! I’m working on the door panels next for a 57 and was considering what route to go. Original nail strips or auveco clips. Now they are just screwed to the door with trim screws. Looks terrible.