Yep, any framebuilder can get you a nice length of 1" threadless steerer tube, and any framebuilder with any approximation of a lathe can spin the little c-clip ring in the bottom for you. I've got thereadless steerers on all my bonty forks. Easier to adjust the HS, lighter, a more connected feeling at the helm, but mostly, I like not having to take a relatively high-precision machine and jam a wedge sideways into the middle of an otherwise evenly loaded steerer tube with enough force to deform everything into chaos. The entire expander wedge setup was the scourge against the machine from the start, and personally I have no problem breaking vintage on any of my bikes with the a threadless rig. Doug Curtlo for instance will happily set you up with some nice true temper steerers, but gene spicer or any of the usual suspects will probably have more time for turning them properly. They're not expensive, so you might think ahead and get a couple, while you're at it.
actually there are probably a few others here who'd be interested in em, and it'd probably help bring the price down if we ordered together. I could use another one too I suppose, and it'd behoove any others interested to get their names in the hat. Let us know what you find out.
fsp