Check to see if an Italian/English stem (22.2 shaft diameter) will fit into your steerer tube. I have two French frames (70s and 80s), and both will take the larger size. If you're dealing with a bare frameset, your “French issues” will be the bottom bracket threading, headset of course, and depending on the front derailer, whether the clamp will get tight enough on the seat tube before it bottoms out.

On the BB, you first have to determine which threading Peugeot used on your frame -- at various times I think that they used French, English or even Swiss. The last variant is the worst, regarding getting a new BB. Velo Orange sells cartridge bearing bottom brackets with French cups, but they have JIS-size (Japan Industrial Standard) tapers on the spindle -- whether that's a problem or not depends on the crank arms you intend to use. French loose-ball BBs aren't really made any more., but it's possible to find them, with some patience. English-threaded BBs are ubiquitous. Swiss are the rarest, and hardest to find.

For the headset, if you have the original fork, you're almost certainly going to need a French headset.

You need to measure the seatpost carefully, or have a shop with a graduated post do that -- there's a fair bit of variation depending on year. Sometimes people have overtightened the clamp to fit an undersize post, and that needs to be opened up, and sometimes re-shaped to be round again. The correct diameter post should fit, with very little clearance when everything's right.

Don't expect any help from your local bike shop, unless you are extremely lucky -- the people there like as not will know nothing about these things, and worse yet, may give you really stupid advice. There are exceptions, but like French threading anymore, they're dwindling.

Check out Miamijim's Peugeot website, and VeloBase.com for components. And ask questions here -- yus'll be back, I guarantee it.