Greetings and welcome from Colorado; and welcome to the vintage Airstream hobby. I find it very enjoyable to renovate these classic travel trailers, and so do thousands of others here on these Forums.
We inheirted the 1986 Limited 34' back in 2005. My wife's folks bought it new and traveled all over North America in the thing in their retirement. I've done some significant repairs and refurbishments to the trailer, but it is mostly original. It has beautiful hickory wood cabinets in it. It is a twin bed layout.
Then I bought a 1966
Trade Wind 24'. It needed a total make over, which took me two winters. It was the old body style and a classic looking thing. I sold it after I finished it and still miss it some.
Hungry for another project, I bought a 75 Overlander 27' twin bed layout just like you did. It too needed extensive repairs as many of these 1970s trailer do. They are repairable and can be built into very comfortable travel trailers. Below are photos of our Overlander now pretty much done, although never completely done. I know the 75 Overlander inside out now.
Navigate these Forums to the Airstream Knowledgebase near the bottom of the Forums page. Then click on Overlander and your year range. There you can stay up all night reading about Overlanders and how folks have renovated them. My "project thread" is linked below and found in the Knowledgebase. But it is not the best project thread by any means.
WBCCI #8607 VAC Region 11
KnowledgeBase trailer renovation threads: 69 Globetrotter, 76 Sovereign, 75 Overlander, 66 Trade Wind Such fun !