gma,
to answer your question, conventional wisdom was always that the eye couldn't perceive more than 15 - 20 lines per millimeter in a print.

Ctein of "Camera and Darkroom" fame claimed a 30 LPM number was more accurate. He also a number of B&W papers and came up with a resolution for the paper of about 45 LPM. Paper is not the limiting factor.
Take care,
Tom