This one's a little puzzling. What's interesting is, the fork seems to be of 1984/85 vintage but for some reason some of the features on this SV frame makes it look older than that, like the traditional non-fastback seat stays,It was the pre-84 PSV that had the non fastback stays....but the double bottle mounts seem to say this is an 85 or newer. The long point windowed lugs is unusual to Peugeot, especailly to SV980 frames. I don't remember them ever having windowed lugs on the PSVs. The BB shell is also different from the plainer/nicer than the one on my 84 PSV.
I always thought that the PSV was their highest 80's model with the SV980 tubing, but this one seems to be a level up, specially with the chrome on the rear triangle. Could it be a special made frame for a racer??.......also could be a high end Euro only SV980 framed model too.
Not really liking that plainish bleu paint on it. I would have done a classic 80's Peugeot metallic Pearl white on it with the traditional black and white racing checker decals from Peugeot if it were my bike (No color banding). But it's still an awesome frame!

Congratulations on the Mystery Peugeot aquisition!
Please do tell us if you find out what it is exactly.

Chombi