You don't need to replace the DO (on or both) there is a genuine Campagnolo hanger bit that's made to repair this "drewed" example. Now the challenge is finding one of THOSE (and the repair shop to braze it). The handlebars with molded-on "pleather" hoods and wrap, most likely the Philippe stem as well, are straight off a late '70s or early '80s Motobecane. Too bad such a nice frame has been mishandled, now you can show it that TLC it deserves.