For starters, I don't think that is actually a Peugeot frame. It should have some sort of model label on the top tube near the seat tube. That fork crown also looks more like it belongs on a bike with horizontal dropouts, plus those vertical dropouts look way too crappy for any Peugeot I've seen. Sure, many 70s Peugeots had stamped steel horizontal dropouts, but not vertical ones which were that low quality. There are a ton of decal sets on electronicbay, so I could see some dummy mislabeling it to get a few more bucks. I recently saw someone with a Rollfast repainted and labeled as a Schwinn. So stupid.
Secondly, it's definitely not worth messing with a chain tensioner if you want a SS. Just get a bike with horizontal dropouts.