Originally Posted by
dweenk
....but it is threaded. The headset is in great shape, so am I risking steerer tube failure by clamping a stem to it?
Yes. and possibly worse.
Threaded steerers have the wall thickness reduced by about by the threads. The design 100% depends on the support of a quill stem inside to buttress the cut tube, and carry stress below the lowest thread.
The possibly worse comes into play if the steerer snaps, while you're riding leaving the bar in your hands, but no longer attached to the fork.