Should I replace these resistors on my vintage radio?
Carbon resistors like what's in your vintage radio are not stable over long time periods. In my experience, the resistance moves upwards. I have noticed this even on early Delco Studebaker solid state car radios that persisted with carbon resistors. Your radio probably has pre-WW2 resistors because WW2 made designers adhere to the preferred range which 250K is not. Due to the age of your radio, I think you should replace all the old resistors. Remember that many small modern resistors do not have the voltage rating. It is good to get the chassis to spec so the valves will all be at their correct bias points.