A few.....

1. I learn as I go.....
2. I've learned a few things in this thread
3. There're exceptions to every 'rule'
4. The OP's bike still has horizontal '531'
5. PY serial seem to be hand stamped before paint....the OP looks to be stamped after paint

I've always said that Peugeot made different models for each market and I've always said that sometimes its impossible to ID a particular bike due to the different models. I absolutely with 100% certainty would NOT BE CONFIDENT calling the OP's bike a 'PY'.

Very simple put, if your trying to sell me a SL65 AMG Mercedes and the emblem on the engine says SL500 I'm going have concerns.

As qd-s mentions, off the rack PY's are very similar to PX's, I've seen this many, many times. I've never seen a cataloged PX with bottle braze-ons until now but these bike are very rare and very clearly the exception to the rule.

I'm also feeling stupid at the moment...the PY on the home page of my website has green lettered '531':