Advantages of Mag?

What are the advantages of running a mag?
Building a 598, doing some different things. Going to Enderle injection and probably dry sump. A460 heads and tunnel ram for the Enderle.

Does it replace the ignition box and alternator?

A Mag it's self is self contained & doesn't need any power or input from the car's elec. system to run, it provides it's own power. Some have an internal transformer, (no external wired parts/devices) and some like the Mallory Super/Sprint Mag stuff has an external wired transformer/coil unit. To shut the engine down a Mag does require one part of it's wiring circuit to be able to be temporarily grounded to the chassis through a simple "start-kill" switch mounted within the driver's reach.

The Mallory stuff can be setup with different internal advance weights, or you can replace the advance weights with an advance lock-out spacer/adapter.