It sort of depends on what your plans for the bike are. If you're rebuilding it for yourself to enjoy a period piece of machinery that can be used and enjoyed without constant attention or fear of the climate stepping in to ruin things, then stainless rims/spokes/fasteners are the way to go. Stainless steel won't give you the ultimate glitter of fine chrome, but the modern stuff is really very good. (Or go down the alloy rim route - like the 60's ton-up boys.) On the other hand, if you're worried about the rivet-counters whispering behind your back that originality has been compromised, then it has to be chrome, but you'll need to source old rims with the Dunlop/Jones stamp and get them replated as the modern stuff is obviously, well, 'modern'.