I often work on radios that are close to being complete trash, so I don’t worry to much about restuffing capacitors and the like. I am more concerned with safety, functionality and if the radio looks decent. I’m less concerned about some hypothetical expert feeling outraged at the presence of a modern yellow capactor below the chassis. In the case of the Brunswick 5NO I am working on, the radio was so trashed (broken cabinet, blown power transformer, fried components, crumbling cloth wire) that just getting it working again (with new components, etc) and making it outwardly look good is, in my mind, a fun challenge and I am happy with the results so far. I document all my changes, but I’ve kept the original circuits. That way, the radio may be serviced in the (hypothetical) future. I am not running a museum nor am I selling to collectors; if I were, it would be different.
Having said that, I have a couple 1920s radios where the condition is good enough and the radio attractive enough that I will try to preserve the original look as much as possible. My Grebe Synchophase needs some work, but I’ll make it look as original as possible. It beautiful, and I don’t want to wreck it.
Also, with early AC sets (like the Brunswick), I *never* trust the old paper capacitors. Some restorers never touch them because “they were so well made!” and “don’t destroy the originality!” Whatever; they are 90 years old and will fail. Unless the plan is to keep it on the shelf as a preserved fragment of history, make the power supply as safe as possible.
In the end, working on these radios is a personal thing and it all ads to “keeping the love of antique radios alive”. The preservers of history and the modern-day tinkerers are equally important.