Normally they sit high by about .003" to compensate for heavy parts between centers and to allow for wear over the years which actually may make it improve. They are hand scraped in at the factory this way and in most cases if it is off, your machine is not leveled correctly and has bow in the center.
I'd get a good precision machinist level and start there. Move the machine to the left and right and see if the level is changing depending on the turret location. Also when re-tightening the bolts on the tailstock be sure to tighten evenly to avoid distortion. (much like head bolts on an engine or lug nuts on a wheel)
This should get you closer to the factory spec.