I just realized I haven't checked in for over three months! Have been working a summer internship, little time to ride anything vintage and absolutely no time to wrench at all, and no speace too in my temporary quarter. Funny how these things go. Anyway, the internship is over, still got my beautiful SOMEC to build and now a few weeks to do it properly. Time to round up te parts (and reconnect with you folks!).

Just a lil' question: what kind of headset would be appropiate for an early nineties, quill stem build? I know Shimano made 600 headsets, but I have a hard time telling which is the most fitting to the 600 tricolor group I'm using. Any suggestions? I'm not stuck on Shimano, just looking for a nice, period correct HS. ISO threads, and nothing too rare, please.

Your available stack height will be your biggest factor. If you put the steerer through the HT with the bottom of the tube touching where the crown would rest how much steerer sticks out the top?

Depending on how ornate the frame and what you intend to build it with I would go with one of the C-Record CampI HS. Some of the late '80s early '90s shimanos had the lowest stack heights though.

For me I have been using a lot of Ritchey logic HSs. They are pretty good quality reasonably priced and don't look too bad.

I don't think you can ever go wrong with a Tange Levin CDS or a Falcon. They aren't as expensive as a period-correct Shimano, but they are very high quality and were found on a lot of nice bikes of the era.

Campagnolo stayed in the game with quill headsets until the early 2000's, and for all I know may still. I bought a Chorus for my Trek 610, replacing a wonky Stronglight B10 (actually a bastardized one), in about 1999, and saw the same part in catalogs for a few more years at least. And Campy would not be wrong for a fine Italian frame like a Somec.

My guess is about $90 now, but I really haven't seen any.

It's still as smooth as glass.

I just used the Velo Orange headset on a mid 80's bike and it looks good, easy to install. Not expensive and was available locally.

VO Alloy Headset, ISO - Headsets - Components

Tange "Levin" headsets are still made, affordable, well constructed, and have a classic look consistent with a bike of that era.

That Tange Falcon looks the part and is of quite-decent quality from my experience.

As Bianchigirl mentioned, stack height must be considered, and I'm pretty sure the Falcon falls well within the "normal" range so worth considering.

Any late-1990's Shimano 1" cartridge model is a particularly durable choice from my own experience, again, with modest stack height,

Here's a headset you might consider that's a great bargain:

Miche Primato needle bearing headset.
Pretty much a copy of Stronglight's needle bearing headsets, but without the sticker shock.
I've seen these for sale at eBay, brand new, at around 45 bucks average, which is easily half of what equivalent NOS Stronglights sell for.
IIRC, the headset also has a lower stack height than most, so it can handle steerer tubes that were cut a bit short.
I have it on one of my bikes, installed about three years ago, and it had performed just as good as my A9's so far. I think its design will also look at home on most 90's bikes with 1" threaded steerers.

I'd look for a 6500 headset. Easy to install, easy to maintain, and generally affordable.
That Miche Primato looks nice. I really like the Primato seat posts.

I'd vote for a needle bearing. I've been using Stronglights for over 30 years. Have over 20000 mile on at least a couple of them. Have yet to replace a bearing.