Well, my mum's got a bike that she got a good 20 or so years ago at her first workplace and the bike's pretty much sat in the garage (back in Hungary though) ever since. It's in a good state but it's old, I'm thinking about 80s as it even has shifters on the stem. She said it was top of the line back then but as I'm no use as to information about old bikes I'll ask this:
Do seat rail diameters vary? We found a comfy looking seat at my LBS for her to replace the old one with but I'm not sure if the rails are the same diameter or not (i.e. if they are interchangeable). Sadly I cannot measure the diameter of the current seat as it's back in Hungary.