A seat tube ding is accessible from the top. I'd try to cold work it myself with a nice little iron bar... If you're willing to replace to tube already, you've got nothing to lose.
You could just ride it as is, too.
Just inherited a nice 531 Claud Butler from the 60's I think. No eylelets and pencil stays. Unfortunately there is nice dent in the middle of the seat tube just above front mech clip height. Otherwise it seems fine.
Any thoughts on restoration? Are there any techniques for fixing dents in situ (I can hear the screams already) or are we definitely looking at a new seat tube? In which case, is it worth it?