Tim,
The main problem is that the SA2760 cone is case hardened - the case hardening process usually causes the component to shrink by about 2 thou per inch of diameter - thus making the cone tight on the stem. In the past, I have resorted to lapping the cone in to the stem. A light smear of fine grinding paste and about 10 - 15 minutes of winding the cone on and off the stem, will have the cone fitting nicely. As is often the case, lapping usually removes more material from the hardened component than from the soft one, so the thread on the head stem will hardly be affected.
Regards,
Eddie.