[Arran]

Mike;
That's one of the issues I can see with regard to the old radio supply places, the polyester film types, not really a problem, but the electrolytics could be. Other then Antique Electronic Supply most of these places have electrolytics that either have no name marked on them or are marked by some mystery brand I have never heard of.
This does not mean that they are garbage capacitors like Xicon, or Capxon, Lelon, etc., but as you say they are likely general purpose ones, with an 85 degree rating. On the other hand Mouser, Digital Key, and Allied, carry Panasonic, Rubicon, United (Nippon) Chemicon, Nichicon, where they have the specs posted right on the website, higher ratings, and most are the same price, if not less, then the mystery brand caps you find elsewhere.
One potential issue that concerns me is with regard to replacing 1/2 watt resistors. Many of the ones on the market have a voltage rating of 250 volts, I would like to find some that are 450 volts or higher but it isn't easy, 350 seems to be the max among common 1/2 watt types. I don't know how they arrive at the voltage ratings on resistors, I guess that is the maximum voltage you can reach, with respect to ground, before they arc over.
Regards
Arran