Hi Worm,
The correct way to set up points would be to use a dwell meter, but I personally have never owned one. Providing you rotor shaft bearings are in good condition and the rotor is not blowing in the wind then set the points 19-21 thou should be as good as you will get, after all the points only open 2 times per cam rev. Dwell becomes more important on 6 cyclinder car etc. [-/
Smallcox