Hello from Colorado: Welcome to the vintage Airstream hobby. Your 73 Sovereign
looks darn good in the photo. I think the body is the most important part of an old Airstream. If a tree falls on it, or it gets rear ended by a dump truck, the trailer is worth much less.
I like working on these old vintage Airstreams also. We have had our 86 Limited since 86. I am currently working on a 75 Overlander 27', which is two sizes smaller than yours. Our trailers are built pretty much alike.
You will find a wealth of information on these Forums. I might suggest you start a "project thread" in the Airstream Trailer Knowledgebase found on the Forums page toward the bottom. Then click on Sovereign
, and click on the year range. I think you will find other folks working on their trailers, and you can share ideas and help one another. I have started a project thread on my 75 Overlander, link below. You might like to take a look. My project is not as extensive as your as my trailer was in pretty good shape when I bought it last year. Nonetheless, it had some areas needing attention. Maybe lots of areas.
WBCCI #8607 VAC Region 11
KnowledgeBase trailer renovation threads: 69 Globetrotter, 76 Sovereign, 75 Overlander, 66 Trade Wind Such fun !