Keith, that hose adapter looks unique and rare too! Was it a original genuine part, or was this adapter custom made by someone who just wanted to use 2 hoses together?
As for saving the bags and having a custom cloth bag? Great idea! I don't blame you, considering those bags are hard to find and there most likely isn't a generic bag manufactured for it, even long ago in the past, as the CA wasn't produced very long. However, those cloth shakeout bags let out A LOT of dust into the bag chamber, and through the motor and exhaust filter. You really should be using those type of bags only on machines with modern electrostatic or HEPA Filtration on the exhaust for that reason.
Since you are saving the original paper bags, I would put them in a vacuum sealed food bag to preserve them if you own one of those devices or have a friend who could do it for you, it would definitely help preserve the paper a long time.
Considering the vacuum only has the fibreglass filter and paper bag for filtration, I would consider trying to find a modern upright or central vacuum HEPA Cloth bag to convert the CA for using HEPA Cloth bags and improve the filtration. Same as some collectors who own Air Way & Vita Vac canisters adapt a Riccar Type F HEPA Cloth bag and use a plastic bag top to make a HEPA Cloth bag for those machines. In fact, I think a Riccar Type F or Kirby HEPA Cloth upright bag would be just the right size. Ask a local vac shop or send Tom Gasko a email to ask him what may work. You already have the cloth shakeout bag and plastic bag top, so you already have the dimensions for whatever size bag you convert would have to be. Simply line the bag chamber with the bag material, put the bag top on top and fold the material over the edge so it's sealed in place and can't leak.