Never used one myself but from what I hear they are not wirth it.
 
The general consensus is to stay with the stock dizzy and swap out the points for a points conversion kit like pertronix or accuspark to achieve an eletronic distributor.
 
 
 
Properly adjusted points are also perfectly fine to use.
 
Dwell angle is 49-55 deg if using points and your timing light has a dwell function.
otherwise for new Points the gap is 0.45-0.55mm