Originally Posted by bostontrevor
This is why threadless was invented... or something like it. They are less flexy though admittedly the way you have your quill set up is pretty pathological. You might see if you can find a quill riser stem. The 1" shaft is going to be the most flexible part, so the less of that you can have showing above the head tube, the better.
If that doesn't play out for you, you could get a quill to threadless adapter and go threadless. This will feel similar to a quill stem fully inserted.
Or get a steel stem. It would definitely be stiffer.
Quill adapters have short quills,so to get the rise he want's would mean an exaggerated stem angle if he can get there at all. Better to try for a fork with longer steerer or get a frame that fits and quit beating this lame horse.