Old electrolytics will usually respond well to being "reformed" - start them at relatively low voltage, and gradually (like over several days) run them up to full rated.
If they go BANG, well, you did put something around to catch the gunk, right? There was a brown line right round the wall of a former shack of mine where a 32uF 500vw let go. Happily, I was in the next room at the time, but it lifted the PSU off the bench to spray the stuff round the room.