Major pitting in bearing cups; what can I replace? I bought a &quot;mystery meat&quot; Peugeot bicycle, it turned out to be 1991 Peugeot &quot;Milano&quot; (couldn't find it in catalogs): 7-speed rear cassette, Shimano 200GS groupset. I disassembled and cleaned everything, replaced the chain and the cassette. I noticed two problems:

The bearing cones and bearing cups have significant pitting on the non-drive side
If I spin the wheel freely while cassette is not spinning, the cassette wobbles ever so slightly, the edge of the largest gear moves maybe 0.5mm back laterally back and forth

For now I've put it all back together, but now that everything has been cleaned and lubed, I can actually hear some noises from rear bearings when riding on a smooth surface; it's synchronous with wheel rotation and I can only hear it when I'm actually on the bicycle.
My question is: what would be the optimal set of components to replace? Should I try to find bearing cups and replace them together with cones? If it's not worth the hassle, what parameters should I take into account when looking for a replacement wheel?
Rear hub is Shimano FH-HG20:

Here's a PDF: https://si.shimano.com/pdfs/ev/EV-FH-HG20-1108A.pdf
Bearing cup:
You should replace the balls for sure.  They're cheap, readily available (from any bike shop -- just take in a sample ball), and would very likely solve most of your problems.
You can also fairly easily replace the cones.  You might have to order them, but they should be reasonably inexpensive.  You may want to replace the axles at the same time (they often come as a set).
Replacing the cups would require replacing the hubs, and, if you hire it done, this is usually more expensive than just replacing the wheels.  But you can likely get several years of service out of the bike with the existing hubs.