I have a Shimano 600 sealed bearing headset on my Merlin. The rest of the bike is DA7400 series, but the 600 headset, which came with the bike, looks nice and works so well I didn't see the point in changing it.

As for other period correct sealed bearing items I have on some bikes. the Mavic 500 series hubs, introduced in 1975. (Chef's kiss!)
https://velobase.com/ViewComponent.a...3-548b73a3d85b



Also a fan of the Bullseye pulleys shown above, introduced in '73.

Hi-E made some neat sealed bearing hubs, though not particularly robust.

O.M.A.S. "big sliding" bottom brackets with Ti spindles if you want to drop some grams.