78 spider tach wiring

[Wvtim]

Hey all working on my car, put a rebuilt engine in it, the engine came with an electromotive ignition system, started it up on a cradle and ran well, haven't fired it up in the car yet, still got a few things to work out but I have a question about the tach wire, from the looks of the wiring diagram it appears the tach was fed from the negative wire on the coil, I no longer have a coil in this car, can I take that negative and hook straight to my electromotive tach connection and will it work my tach without an amplifier. The electromotive says for some older cars you may need an amplifier to work the tach correctly.
Thanks for lookin and any advice
Tim