I second or third the recommendation to avoid those thick tubed aluminum racks for your application. I bought the Tubus Vega in silver and the large diameter of tubing was incongruous with vintage bike. Also the rear dropout attachment is spaced at 135mm, quite a difference than the likely 120mm on your Peugeot. I didn’t mount that Tubus rack for those reasons. VO contructeur in polished stainless would look a lot better.
Good luck. Nice Peugeot.