MSD Digital-6 Plus and Crane Fireball control modules.
 

What exactly do these ignition control boxes do? Just provide better and more controlled firing of the plugs?

well the msd stands for multiple spark discharge, meaning it puts out up to three sparks per firing. with upgraded coil(s) its even more efficient. i'm not exactly sure about the crane though...

you should have 400RWHP before u think about igniton, cuz it really wont do much if nething, unless ure spraying. if you dont need a bigger fuel pump u dont need more spark.

on your engine an msd box is kinda overkill, now on say my '75 it would help