I have pretty much the same model as you. Started out just trying to do a refresh but am pretty much gutting and starting over. I've decided there really isn't anything special about 1978 anything so it will get new everything including a different floor plan that will suit my wife and I better than the mid-twin rear bath layout.
I'm also a mechanic so I can confidently say you'll be fine with this project. Just take your time and think things through before you start cutting
This forum is the place to be for advice since there are many who have been there and done that. But, don't be afraid to do things the way you want even if others say you shouldn't. It's your trailer and ultimately it'll need to make you happy.
Involve your spouse as much as you can even if it drives both of you nuts. It'll be worth it when you're out on the road and something isn't quite right to be able to say "we talked about that, didn't we?"
Read, read, and read some more. Almost everything on this site that applies to Airstreams will apply to your trailer, even some of the stuff that doesn't make sense for the same model year for them applies to our trailers since they were test beds for Airstream.
Good luck and remember to wear a mask and gloves