'84 Tach Wiring Question

[SCrescue]

I have an '84 Targa with a '79 3.0. No DME computer, running an MSD spark box.

My understanding is that the '84 tach is wired to run off the DME computer, is this correct? I assume I can simply run a wire direct from the MSD to the tach, is this a correct assumption? If so, which terminal do I connect to on the back of the tach? Thx

Mike...