Back in the day my BIL had a real '69 Z-28 & ran a dual point Mallory dizzy, that car was wicked fast. That's where I learned to tune them! Easy... just divide the dwell by 2 & use a feeler gause! Even easier if you use a dwell meter! I had a lil Sun tune up kit with, dwell, timing light & vacuum gauge that I used... still have it & it still works after 40+ yrs!
BoB
BoB