Is there an easier way to use my factory tach in my 70 challenger? I'm using the Hotwire setup, and they recommend the msd adapter and the Dakota digital tach box.

As far as I know, that is your best option. You do not want to go with the Autometer tach adapter 9117, as it requires that you splice into all eight of your coil pack leads.

I am running the dakota digital SGI-8E and the MSD tach signal GMR pickup PART# 8918 to supply a tachometer signal to a Aeromotive billet fuel pump controller.

Thanks for the reply.
I guess that's route I'll take.

It is pretty straightforward. You will clip the MSD pickup on one of your fuel injector wires, probably cylinder #7, and set the dakota digital device up by telling it you are running a one cylinder engine and want to communicate with an eight cylinder tachometer.