If you are referring to running your factory tach, they make a tach adapter which allows you to run your factory tach off of the msd box. With the CD ignitions, you cannot run your tach off of the coil and only certain tach are compatible with the msd boxes otherwise you'll need the adapter.
The ready to run dizzy will allow you to run your tach off of your coil
So, am I correct in assuming that I will have to run one of their boxes to operate a tach? I had been thinking of the ready to run dizzy with no box.