Serial number records have mostly been compiled by later researchers like Phil Nuytten and Mark Howell. Records from US Divers don't exist or were destroyed in a fire during the 70's as I understand it.
Finding one outside of the range of what is recorded is not unusual and I'm sure as time goes along and the internet makes the world smaller more will be added to the rolls.
A couple of back issues of HDS magazine really help with the study of the history of the Aqua Lung. Number 42, Winter 2005, Volume 13, Issue 1 and Number 34, Volume 11, Issue 1 are a great place to start and may be available in their backorder catalog.
I'm not aware of any in depth studies of the Royal Master or Royal Aqua Master.
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB