I'll second the above, faster starting, hotter spark, no points. That said you may not get the performance you expect. Seems that starting in about 1968 (points) distributors started losing centrifugal advance and vacuum advance. As an example 63 292 six distributor is 0@600, 14@1500, 28@3700, vac adv 6@4-7 pounds, 23@13-14 pounds a 1976 distributor is 0@1100, 6@2000, 14@2300, 24@4100, vac adv 0@10-12 pounds, 10@13-14 pounds. The distributor can be recurved to get back what you lose. I need copies of the distributor data in a few more shop manuals for a better understanding of how far it goes. I would have the HEI recurved to the 58 distributor. If your compression, cam, carb have been changed then the curve needs changed or live with it.
Larry
