I have a bike with NR rear and a 10sp Shimano Ultegra cassette and chain. The bike is 126 spacing but the wheel is 130. The shifters are downtube NR. The crank and chainrings are Chorus 10 speed.
This works better than any other combination I've ever used, both indexed and non-indexed. My all Chorus 10speed setup does not shift as well. You gently push or pull the shifter a small amount and it shifts silently. You don't get stuck in between gears as the spacing is so small. It is all dead silent, both while pedaling and while coasting.
10 speed cassettes and chains shift much better than the old stuff because of the cog profiles. They work as a system. The 126 spacing is easily spread to take a 130 wheel. I wouldn't bother with re-centering the rim or adding spacers or cold setting. The only problem I have is that I can't use the largest cog as the derailleur goes into the spokes no matter how I adjust it. In that case I have 9 speeds 12-23 instead of 10 speed 12-25. I could get a different cassette, but it isn't important.
It is important to use new cables and housing to get this to work as old cables just won't shift smoothly enough. Even the slightest binding will make for poor shifting.