Up dating the electrical systems on older Airstream, is not really a huge problem.
One of the simple ways, is to purchase a "service book" for a 1975 to 1980.
That book will show what was installed in those coaches when manufactured.
Up grading the "Univolt" from the older 12-19 volt AC transformer or the original 30 amp Univolt, to what is very common today, namely a 55 or 60 ampere Univolt. Installing a separate fuse panel for it in a convenient place, is a good idea.
Use a 12 volt
fuse panel that is of good quality to avoid down the road failures.
Certainly replace the circuit breaker panel with one that has 4 circuit breakers in it.
1 30 amp main, and 3 20 amp individual breakers. One for the AC, one for the left side of the trailer, and one for the right side of the trailer.
Make SUPER SURE that all wiring within the walls, goes through grommets.