I don't know enough to really be commenting, but I will anyway.
My 250 has some nice looking, modern gold-plated RCA jacks in place of the originals, which the previous owner told me were some kind of porcelain and had cracked due to age. I think that is a nice upgrade.
I have also heard that it is possible to replace the meter lamps with LEDs that are brighter and more reliable than the stock lamps. I'd like to learn more about this.
Replacing electrolytic capacitors is probably a good idea in an amp of this vintage. But that is a topic that generates some heated discussion on both sides- lots of people will tell you "don't fix it if it ain't broke", and some will say that cap replacement can negatively impact the vintage warm sonic characteristics that we love. Personally, I do not buy into this latter point of view, after my limited experience with cap replacement produced dramatic improvements in sound.
I'll watch your thread to see what others suggest. I have decided to keep my 250 for now- I got it as part of deal in which my main interest was the tuner, but this amp is so cool looking it is hard to let go of!