Nutted axles, steel rims, no chrome, cottered crank = AO8 or similar. I can't make out the headtube lug details, that would be the only question I would have.

Updates on a 1970s Peugeot can be somewhat expensive, due to unique obsolete French parts. Its getting better, there are a couple of choices out there, but the prices are significantly higher, and choices are very limited. Updating/upgrading bikes that used current standard sizing can be much cheaper.

But if you are happy with it as it is, then just the basic bearings/grease/cables and housings maintenance is all that is required. Nothing unique on any of those parts, so that should be an easy undertaking.

The chain is a cheap standard part, around here I can buy a new chain for that bike for less than $5.