There is a better piece of equipment, the
Innicycles adapter, which combines the headset AND the quill adapter.
What it basically does, is replace your quill stem and headset with a combined unit that has excellent sealed bearings and very easy adjustment.
It has an inner quill that fits down inside the steerer of the fork, like any other quill stem, but around that is a threaded "sleeve" that fits down over the outside of the fork steerer, and threads onto it. That is bonded to the top cups of a headset, so when you spin it down, it combines with the bottom cup/bearing, the fork steerer, and the top cup/bearing to create both an easily adjusted, really good quality headset, with a steerer.
The steerer is then 1 1/8, which fits almost all modern stems. I'm not sure if they would produce one in 1", as the majority of the spacers and stems now go 2x 1 1/8".
In this case, the fork can be the OEM fork, or can actually be a bit shorter, as long as it gets up there to the top of the head tube or so, but it doesn't have to go the full 3/4" or so above it that many older headsets require.
And, unlike a modern threadless setup, the stem is NOT required to keep both the headset tight and the bar straight. The adapter takes care of the headset, and the stem simply holds the bar onto the stem. There is a quill bolt, as well, with a cone nut. I doubt it's really needed, but this piece of bike gear is engineered for the long run.
joejack951 here on BF invented them and sells them. They come in black and satin silver.
A long time ago, the first adapter I used was 1". Haven't seen it in years, used it on a Kestrel. I've only see 1 1/8" since, and some even bigger ones, not sure what they were for.
As far as using a modern 1 1/8" stem for a 25.4 or 26.0 bar, there are stems out there that do just that.
